kondave,
RDP uses completely different IP ports than SMB (Windows File/Printer sharing protocol for Microsoft Networks) so if you can ping and RDP works - this means there's IP connectivity between those PCs - but something is not right with Vista's network settings or file/print sharing configuration.
Have you tried creating shared folders or printers on the Vista PC? If so, can you connect to the Vista PC to these shares from the XP PC?
Have you verified the share permissions on the XP machine? Are the usernames/passwords identical on BOTH the XP and Vista PC? Do you have the built-in firewall enabled on either PC? If so, have you opened up File/Print sharing on both firewalls. Sorry if I'm asking about things you've already tried.
Look at this site and make sure there's nothing you missed:
http://technet.microsoft.com/en-us/l.../bb727037.aspx
If this doesn't help, here's another thing to try on your vista PC (works only with Vista HOME versions):
NOTE: This is for Vista Home versions.
1. Open the Start Menu.
2. In the white line (Start Search) area, type regedit and press Enter.
3. Click Continue for UAC prompt.
4. In regedit, go to: -HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa
5. In the right pane, right click LmCompatibilityLevel and click Modify.
NOTE: If it doesn't already exist, create a DWORD value named
LmCompatibilityLevel
6. Set the value to 1
7. Reboot
Hope this helps.
- John