I like Spybot Search and Destroy for anti-spyware stuff.
Windows Live One works pretty well (only one that fixed my friend's computer today).
I like bullguard antivirus.
If you have something relatively nasty, try running combofix (just google the name, and you'll find a lot on it). combofix kills all the really nasty viruses, considering it's pretty much a collection of programs designed to kill individual viruses, as far as I can tell.