I would whole heartedly agree with nihil on this one. MalwareBytes AntiMalware is incredible.
Spybot S&D is pretty good too. I love the immunize feature. Though that goes back to the blacklist vs whitelist issue.
I don't have much experience with A-Squared, but I have heard good things about it.
Usually, I will run a MalwareBytes quick scan in safemode, then boot into normal mode and do a full scan with it. If items are still found on the full scan, I will reboot, and do a full scan again. If malicious items are still found, I usually start thinking about backing up, and reloading the OS.
I have gotten to the point with my systems, where if I have an infection, it is easier to reload than to fight it. I have backups of just about everything I would need in that event. If I am bored, and just want to see what these things are doing, I will grab a copy of SecCheck [http://www.mynetwatchman.com/tools/sc/], and Mandiant Highlighter [http://www.mandiant.com/products/fre.../highlighter/], and try to figure out which files/processes etc are causing the problem. It can make a dull evening pretty interesting. I have a couple of VMs that I use just for checking out infections.