Don't run HijackThis FIRST. Save it for later. Let's see what we can get rid of using some tools first
Moissonite has given you a link to SpyBot Search and Destroy. Get that first, and run its update program. Then boot into safe mode and delete what it finds.
I will get back to you with a couple of other ideas.
Update them and run them in safe mode as well. OH............SwatIT takes a long time but is very thorough.
Then try CWShredder.............I will post the link in a moment