OH..wow..I would have never imagine you having an infection in NTLDR.
No wonder why we could not find the infection. It was in the boot loader.
Problem is, the Rescue Disc probably deleted or modified the boot loader. So, we will have to fix that.
This is one of three possible problems:
-MBR is damaged (fixable).
-Corrupt NTLDR file (fixable).
-Misconfiguration of boot.ini file (fixable).
Now, I don't quite remember...did you have an XP CD or not? Either way, we can still work on the system.
Let me know that, so we can continue diagnosing and fixing the issue at hand.