I am new to mac's and have upgrade from Snow Leopard to Lion but......

Question

I am new to mac's and have upgrade from Snow Leopard to Lion but not all my application will work. Is it save to reinstall using original snow leopard dvd and does it wipe all my other application like apature? I am in a panic over this, any help!!
I came across this online and i want to know is it safe to do this:
Backup your User folders to an external drive. This should preserve your documents, photos, music, etc. If you store those things in locations not in the User folder, make sure to copy those over too.
Insert the Snow Leopard disc. Restart your Mac and hold down C to boot to your DVD drive.
Go to Utilities in the menu bar once the installer pops up and select “Disk Utility.”
Find the drive in the sidebar where Lion is installed, select it and navigate to the Partition tab.
Click on the drop down menu under Partition Layout and select “1 Partition.” Hit Apply.
Now navigate to the Erase tab and make sure “Mac OS Extended (Journaled)” is selected, then hit Erase to delete all data on the drive.
Quit Disk Utility to get back to the Snow Leopard installer and proceed with the install.
Restore your User folder and documents from your backup.
Run Software Update to get everything current, install your apps from your original install media and update those as well.
if any one can help me that would be great, thanks Mike

Answer 1

Before you do that why not do this first:
Repair the Hard Drive and Permissions
Boot from your Lion Recovery HD. When the recovery menu appears select Disk Utility. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list.  In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive.  If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the main menu.
To boot from the Recovery HD restart the computer. After the chime hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.
If this doesn't help, then you can proceed to reinstall Snow Leopard as follows:
Downgrade Lion to Snow Leopard
1.  Boot from your Snow Leopard Installer Disc. After the installer loads select your language and click on the Continue button.  When the menu bar appears select Disk Utility from the Utilities menu.
2. After DU loads select your hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Note the SMART status of the drive in DU's status area.  If it does not say "Verified" then the drive is failing or has failed and will need replacing.  SMART info will not be reported  on external drives. Otherwise, click on the Partition tab in the DU main window.
3. Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Set the format type to Mac OS Extended (Journaled.) Click on the Options button, set the partition scheme to GUID then click on the OK button. Click on the Partition button and wait until the process has completed.
4. Quit DU and return to the installer. Install Snow Leopard.
This will erase the whole drive so be sure to backup your files if you don't have a backup already. If you have performed a TM backup using Lion be aware that you cannot restore from that backup in Snow Leopard. I suggest you make a separate backup using Carbon Copy Cloner 3.4.1.
This will erase the drive so be sure to backup your files before doing this.