If you re-install xp, you could have the same problem after 10mins online!. Here's what i would do:
Install, AVG anti virus (Free edition), Sygate personal firewall (Free edition), ad-aware, Spybot search and destroy and Spyware blaster. After installing them, update them all and THEN run them all in turn.
I would also erase all temporary internet files including history and definatley all cookies.
If all this fails, you could always go the route of turning off system restore as trojans can hide in the restore points. Before doing this you should know that you will have no way of restoring your pc to an earlier setting as all the restore points will be erased!
