Here is my GridBagLayout version of the code

Question

     public void constructGUI()
           c= getContentPane();
          //Construct the menus and their listeners
          JMenu filemenu = new JMenu("File");
          JMenuItem saveas= new JMenuItem ("Save Amortization As");
          saveas.addActionListener(new ActionListener(){
               public void actionPerformed (ActionEvent e)
                    JFileChooser filechooser = new JFileChooser ();
                    filechooser.setFileSelectionMode ( JFileChooser.FILES_ONLY);
                    int result = filechooser.showSaveDialog (null);
                    if (result== JFileChooser.CANCEL_OPTION)
                         return;
                    File filename = filechooser.getSelectedFile();
                    if (filename==null||filename.getName().equals (" "))
                         JOptionPane.showMessageDialog( null, "Invalid File Name", "Invalid FileName", JOptionPane.ERROR_MESSAGE );
                    else {
                         try
                              System.out.println("I am ready to create the streams");
                              FileOutputStream file = new FileOutputStream(filename, true);
                              OutputStreamWriter filestream = new OutputStreamWriter(new BufferedOutputStream(file));
                              String info= "The data is based on"+"\n";
                              filestream.write(info);
                              System.out.println("I wrote the first string called info");
                              String interestdata= "INTEREST:"+" "+interest+"\n";
                              filestream.write(interestdata);
                              String timedata="The amortization period is:"+" "+time+"\n";
                              filestream.write(timedata);
                              String loandata="The money borrowed is:"+" "+moneyFormat.format(loannumber)+"\n";
                              filestream.write(loandata);
                              String totals= "Total of Payments Made:"+" " +moneyFormat.format(totalpayments)+"\n"+"Total Interest Paid:"+"  "+moneyFormat.format(totalinterest)+"\n";
                              filestream.write(totals);
                              String filestring = "PAYMENT NUMBER"+"   " + "PAYMENT" + "   " + " PRINCIPLE" + "   " + "INTEREST" +"   " + " BALANCE" + "\n";
                              filestream.write(filestring);
                              double loannumberkf= loannumber;
                              System.out.println(timenumber);
                              for (int j=1; j<=timenumber ; j++ )
                                   double principlekf=payment-loannumberkf*z;
                                   double balancef=loannumberkf-principlekf;
                                   String display ="\n"+ Integer.toString(j)+"                " + moneyFormat.format(payment)+"        "+ moneyFormat.format(principlekf)+ "     "+moneyFormat.format(loannumberkf*z)+ "     "+ moneyFormat.format(balancef)+"\n";
                                   filestream.write(display);
                                   loannumberkf=loannumberkf-principlekf;
                              filestream.flush();
                              file.close();
                         catch ( IOException ioException )
                              JOptionPane.showMessageDialog (null, "File Does not exist", "Invalid File Name", JOptionPane.ERROR_MESSAGE);
                    }//end of else
             } //end anonymous inner class
          filemenu.add(saveas);
          JMenuItem exit= new JMenuItem ("Exit");
          exit.addActionListener( new ActionListener() {
                    public void actionPerformed (ActionEvent e)
                         System.exit(0);
               } //end anonymous inner class
          ); // end call to ActionListener
          filemenu.add(exit);
          JMenuItem summaries=new JMenuItem ("Save Summaries As");
          MenuHandler menuhandler= new MenuHandler();
          summaries.addActionListener(menuhandler);
          filemenu.add(summaries);
          //construct the second JMenu
          JMenu colorchooser=new JMenu("Color Chooser");
          JMenuItem colorchooseritem=new JMenuItem("Choose Color");
          colorchooseritem.addActionListener (new ActionListener() {
                              public void actionPerformed(ActionEvent e)
                                   color=JColorChooser.showDialog(Mortgagecalculation.this, "Choose a Color", color);
                                   c.setBackground(color);
                                   c.repaint();
                     ); //end of registration
          colorchooser.add(colorchooseritem);
          //third menu
          JMenu service = new JMenu("Services");
          JMenuItem s1= new JMenuItem ("Display Amortization");
          JMenuItem s2= new JMenuItem ("Calender");
          service.add(s1);
          service.add(s2);
          //Create menu bar and add the two JMenu objects
          JMenuBar menubar = new JMenuBar();
          setJMenuBar(menubar);
          menubar.add(filemenu); // end of menu construction
          menubar.add(colorchooser);
          menubar.add(service);
          //set the layout manager for the JFrame
          gbLayout = new GridBagLayout();
          c.setLayout(gbLayout);
          gbConstraints = new GridBagConstraints();
          //construct table and place it on the North part of the Frame
          JLabel tablelabel=new JLabel ("The Table below displays amortization values after you press O.K. on the payments window. Payments window appears after you enter the values for rate, period and loan");
          mydefaulttable = new DefaultTableModel();
               mydefaulttable.addColumn("PAYMENT NUMBER");
               mydefaulttable.addColumn ("PAYMENT AMOUNT");
               mydefaulttable.addColumn ("PRINCIPLE");
               mydefaulttable.addColumn ("INTEREST");
               mydefaulttable.addColumn("LOAN BALANCE");
          Box tablebox=Box.createVerticalBox();   
          mytable=new JTable(mydefaulttable);
          tablelabel.setLabelFor(mytable);
          JScrollPane myscrollpane= new JScrollPane (mytable);
          tablebox.add(tablelabel);
          tablebox.add(myscrollpane);
          //gbConstraints.weightx = 100;
          //gbConstraints.weighty = 50;
          //gbConstraints.fill = GridBagConstraints.BOTH;
          gbConstraints.anchor = GridBagConstraints.NORTH;
          addComponent(tablebox,0,0,3,1,GridBagConstraints.NORTH);
        //c.add (tablebox, BorderLayout.NORTH);
          //create center panel
          JLabel panellabel=new JLabel("Summarries");
          MyPanel panel =new MyPanel();
          panel.setSize (10, 50);
          panel.setBackground(Color.red);
          panellabel.setLabelFor(panel);
          Box panelbox=Box.createVerticalBox();
          panelbox.add(panellabel);
          panelbox.add(panel);
          //gbConstraints.weightx = 50;
          //gbConstraints.weighty = 100;
        //gbConstraints.fill = GridBagConstraints.BOTH;
          gbConstraints.anchor = GridBagConstraints.CENTER;
          addComponent(panelbox,1,1,1,1,GridBagConstraints.CENTER);
          //c.add (panelbox, BorderLayout.CENTER);
          //add time in the SOUTH part of the Frame
          Panel southpanel=new Panel();
          southpanel.setBackground(Color.magenta);
          Date time=new Date();
          String timestring=DateFormat.getDateTimeInstance().format(time);
          TextField timefield=new TextField("The Date and Time in Chicago is:"+" "+timestring, 50);
          southpanel.add(timefield);
          //gbConstraints.weightx = 100;
          //gbConstraints.weighty = 1;
          //gbConstraints.fill = GridBagConstraints.HORIZONTAL;
          gbConstraints.anchor = GridBagConstraints.SOUTH;
          addComponent(southpanel,0,2,3,1,GridBagConstraints.SOUTH);
          //c.add(southpanel, BorderLayout.SOUTH);
          //USE "BOX LAYOUT MANAGER" TO ARRANGE COMPONENTS LEFT TO RIGHT WITHIN THE SOUTH PART OF THE FRAME
          //Create a text area to output more information about the application.Place it in a box and place box EAST
          Font f=new Font("Serif", Font.ITALIC+Font.BOLD, 16);
          string="-If you would like to exit this program\n"+
          "-click on the exit menu item \n"+
               "-if you would like to save the table as a text file \n"+
               "-click on Save As menu item \n"+"-You can reenter new values for calculation\n"+
               " as many times as you would like.\n"+
               "-You can save the summaries also on a different file\n"+
               "-Files are appended";
          JLabel infolabel= new JLabel ("Information About this Application", JLabel.RIGHT);
          JTextArea textarea=new JTextArea(25,25);
          textarea.setFont(f);
          textarea.append(string);
          infolabel.setLabelFor(textarea);
          Box box =Box.createVerticalBox();
          box.add(infolabel);
          box.add(new JScrollPane (textarea));
          //gbConstraints.weightx = 50;
          //gbConstraints.weighty = 100;
          //gbConstraints.fill = GridBagConstraints.BOTH;
          gbConstraints.anchor = GridBagConstraints.SOUTHEAST;
          addComponent(box,2,1,1,1,GridBagConstraints.SOUTHEAST);
          //c.add(box, BorderLayout.EAST);
          //Create the text fields for entering data and place them in a box WEST
          Panel panelwest = new Panel();
          //create the first panelwest and place the text fields in it
          Box box1=Box.createVerticalBox();
          JLabel rate= new JLabel ("Enter Rate", JLabel.RIGHT);
          interestfield=new JTextField ("Enter Interest here and press Enter", 15);
          rate.setLabelFor(interestfield);
          box1.add(rate);
          box1.add(interestfield);
          JLabel period=new JLabel("Enter Amortization Periods", JLabel.RIGHT);
          timenumberfield=new JTextField("Enter amortization period in months and press Enter", 15);
          period.setLabelFor(timenumberfield);
          box1.add(period);
          box1.add(timenumberfield);
          JLabel loan=new JLabel("Enter Present Value of Loan", JLabel.RIGHT);
          loanamountfield =new JTextField ("Enter amount of loan and press Enter", 15);
          loan.setLabelFor(loanamountfield);
          box1.add(loan);
          box1.add(loanamountfield);
          JLabel submit = new JLabel("Press Submit Button to Calculate", JLabel.RIGHT);
          submitbutton= new JButton("SUBMIT");
          submit.setLabelFor(submitbutton);
          box1.add(submit);
          box1.add(submitbutton);
          panelwest.add(box1);
          //Add the panel to the content pane
          //gbConstraints.weightx = 50;
          //gbConstraints.weighty = 100;
          //gbConstraints.fill = GridBagConstraints.BOTH;
          gbConstraints.anchor = GridBagConstraints.SOUTHWEST;
          addComponent(panelwest,0,1,1,1,GridBagConstraints.SOUTHWEST);
          //c.add(panelwest, BorderLayout.WEST);
          //Event handler registration for text fields and submit button
          TextFieldHandler handler=new TextFieldHandler();
          interestfield.addActionListener(handler);
          timenumberfield.addActionListener(handler);
          loanamountfield.addActionListener(handler);
          submitbutton.addActionListener(handler);
          setSize(1000, 700);   
          setVisible(true);
          System.out.println("repainting table, constructor");
          System.out.println("I finished repainting. End of ConstructGUI");
     } // END OF CONSTUCTGUI
     // addComponent() is developed here
     private void addComponent(Component com,int row,int column,int width,int height,int ancor)
          //set gridx and gridy
          gbConstraints.gridx = column;
          gbConstraints.gridy = row;
          //set gridwidth and gridheight
          gbConstraints.gridwidth = width;
          gbConstraints.gridheight = height;
          gbConstraints.anchor = ancor;
          //set constraints
          gbLayout.setConstraints(com,gbConstraints);
          c.add(com);          
     

Answer 1

Quit cross-posting (in different forums) every time you have a question.
Quit multi-posting (asking the same questions twice) when you ask a question.
Start responding to your old questions indicating whether the answers you have been given have been helpfull or not.
Read the tutorial before asking a question. Start with [url http://java.sun.com/docs/books/tutorial/uiswing/layout/visual.html]How to Use GridBag Layout. Of course its the most difficult Layout Manager to master so I would recommend you use various combinations of the other layout managers to achieve your desired results.
If you need further help then you need to create a [url http://homepage1.nifty.com/algafield/sscce.html]Short, Self Contained, Compilable and Executable, Example Program (SSCCE) that demonstrates the incorrect behaviour, because I can't guess exactly what you are doing based on the information provided.
And don't forget to use the [url http://forum.java.sun.com/help.jspa?sec=formatting]Code Formatting Tags so the code retains its original formatting.