correct me if i'm wrong but,system restore should bring your system back to the state it was before you got hijacked.
No, usually these things add themselves to the restore folder. Usually there is some trace of them even if you think they are completely wiped. Xp seems to store some info in index.dat that cannot be erased. If you got something from a website, you can count that it will have some type of info there and it will restore a bad cookie and you will probably get some bad stuff again. I have not tried a program to erase index.dat, but manually doing it does not work in XP.