I agree with what Viper said.
I would add "Spyblaster" to the list also,
and absolutely you should add "WinPatrol" also. It guards your startup files, and prevents any new programs starting up without your permission. It is the safety net for anything that might slip past the other programs. I've used all these for a long time, and they work great.
Since you already apparently have a problem, I agree with Viper, definitely do your first scans in safe-mode, since a lot of the garbage out there is designed to prevent anti-spyware and anti-virus programs from accessing their files.