If your infection is proving hard to remove run SmitfraudFix following the guide below.
Malwarebytes: http://www.malwarebytes.org/mbam.php
SuperantiSpyware: http://www.superantispyware.com/
Avast Anti-Virus: http://www.avast.com/eng/avast_4_home.ht...
SmitfraudFix: http://siri.geekstogo.com/SmitfraudFix.e...
Guide to using SmitfraudFix: http://www.bleepingcomputer.com/forums/t...
To protect your PC in the future you need to use anti-virus software and a firewall, id recommend using Avast and Comodo Pro firewall both are very effective and completely free, you should also switch to Firefox 3 if you are browsing with IE as its much safer.
Also, Spybot Search and Destroy will get it without a problem (I use it a lot).
Lastly, download HIJACK THIS run it first to log the registry and boot info for stuff running. After the PC appears to be clean, run HiJack this again and compare the 2 logs making sure not to have assigned the logs the same name.
If you are not got with this operation, find a friend who knows a little.
got=good