1841 router ios upgrade from Version 12.4(1c) to c1841-ipbase-mz.151-4.M5?suggest the right memory for this?

Question

hi here my router configuration with memory details,i need to upgrade to 15.1 but i uploaded the 15.1 os by using TFTP server but not upgraded.server returned error?
Router#show version
Cisco IOS Software, 1841 Software (C1841-IPBASE-M), Version 12.4(1c), RELEASE SO
FTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2005 by Cisco Systems, Inc.
Compiled Tue 25-Oct-05 17:10 by evmiller
ROM: System Bootstrap, Version 12.3(8r)T9, RELEASE SOFTWARE (fc1)
Router uptime is 0 minutes
System returned to ROM by power-on
System image file is "flash:c1841-ipbase-mz.124-1c.bin"
Cisco 1841 (revision 6.0) with 114688K/16384K bytes of memory.
Processor board ID FHK10411A72
2 FastEthernet interfaces
DRAM configuration is 64 bits wide with parity disabled.
191K bytes of NVRAM.
31360K bytes of ATA CompactFlash (Read/Write)
Configuration register is 0x2102
Router#show flash:
-#- --length-- -----date/time------ path
1     13937472 Oct 15 2006 06:32:34 +00:00 c1841-ipbase-mz.124-1c.bin
2         1821 Oct 15 2006 06:46:38 +00:00 sdmconfig-18xx.cfg
3      4734464 Oct 15 2006 06:47:28 +00:00 sdm.tar
4       833024 Oct 15 2006 06:48:00 +00:00 es.tar
5      1052160 Oct 15 2006 06:48:34 +00:00 common.tar
6         1038 Oct 15 2006 06:48:58 +00:00 home.shtml
7       102400 Oct 15 2006 06:49:24 +00:00 home.tar
8       491213 Oct 15 2006 06:49:50 +00:00 128MB.sdf
9      1684577 Oct 15 2006 06:50:30 +00:00 securedesktop-ios-3.1.1.27-k9.pkg
10      398305 Oct 15 2006 06:51:06 +00:00 sslclient-win-1.1.0.154.pkg
8679424 bytes available (23252992 bytes used)
Router#dir flash:
Directory of flash:/
    1  -rw-    13937472  Oct 15 2006 06:32:34 +00:00  c1841-ipbase-mz.124-1c.bin
    2  -rw-        1821  Oct 15 2006 06:46:38 +00:00  sdmconfig-18xx.cfg
    3  -rw-     4734464  Oct 15 2006 06:47:28 +00:00  sdm.tar
    4  -rw-      833024  Oct 15 2006 06:48:00 +00:00  es.tar
    5  -rw-     1052160  Oct 15 2006 06:48:34 +00:00  common.tar
    6  -rw-        1038  Oct 15 2006 06:48:58 +00:00  home.shtml
    7  -rw-      102400  Oct 15 2006 06:49:24 +00:00  home.tar
    8  -rw-      491213  Oct 15 2006 06:49:50 +00:00  128MB.sdf
    9  -rw-     1684577  Oct 15 2006 06:50:30 +00:00  securedesktop-ios-3.1.1.27
-k9.pkg
   10  -rw-      398305  Oct 15 2006 06:51:06 +00:00  sslclient-win-1.1.0.154.pk
g
31932416 bytes total (8679424 bytes free)
Router#dir nvram:
Directory of nvram:/
  190  -rw-         633                    <no date>  startup-config
  191  ----           5                    <no date>  private-config
  192  -rw-         633                    <no date>  underlying-config
    1  -rw-           0                    <no date>  ifIndex-table
    2  ----          12                    <no date>  persistent-data
196600 bytes total (193862 bytes free)

Answer 1

thank you,
i have deleted my flash using command "delete flash:"
before i deleting my IOS i issued show flash: and it lists all files with IOS file.
after i delete the flash then i downloaded IOS image to flash after that i gave the show flash command and i m only able to see IOS image ,not the below files"i.e:sdmconfig-2811.cfg,es.tar,common.tar,home.shtml,home.tar,128MB.sdf,securedesktop-ios-3.1.1.45-k9.pkg,sslclient-win-1.1.4.176.pkg"
could you plz tell me what are these files,
in my new flash i m having my IOS only,the above bolded files are not present.Is it a problem?
Router#sho flas
-#- --length-- -----date/time------ path
1     40617068 May 2 2008 05:38:36 +00:00 c2800nm-advipservicesk9-mz.124-9.T7.bi
n
2         2748 May 2 2008 05:49:56 +00:00 sdmconfig-2811.cfg
3       931840 May 2 2008 05:50:14 +00:00 es.tar
4      1505280 May 2 2008 05:50:36 +00:00 common.tar
5         1038 May 2 2008 05:50:52 +00:00 home.shtml
6       112640 May 2 2008 05:51:06 +00:00 home.tar
7       527849 May 2 2008 05:51:24 +00:00 128MB.sdf
8      1697952 May 2 2008 05:51:48 +00:00 securedesktop-ios-3.1.1.45-k9.pkg
9       415956 May 2 2008 05:52:08 +00:00 sslclient-win-1.1.4.176.pkg
18186240 bytes available (45830144 bytes used)