The usual course of these things is, one will be better for awhile, then another, and the best bet is to keep all of them on hand for use when one isn't cutting it any more.
With my main PC I don't participate in very many risky behaviors so it seems to stay free of various malware so I don't bother with any software. I have plenty of friends who have all kinds of problems though. Rather than try to walk them through anything lately I've been sending them all to http://onecare.live.com
If you visit the link and look on the left in the menu you'll see "safety scanner" click that, then there is a link for a free full service or quick scan. You do not have to pay, you just agree, and allow them to install the components.
It does a pretty good job. Looks for and removes viruses, spyware, orphaned registry entries, temp files, etc.
Ps1on, the problem you described with the copy of a\v reporting clean isn't too unusual for an infected machine. The virus writers know the commonly used names of the executables and other files associated with the a\v apps. Some intentionally instruct the virus to target and compromise those first. At a more sophisticated level they leave them to appear to be operating normally, but to stop getting new defs or applying them. That's why I prefer the web based scanner like the one provided by microsoft there. Takes a little longer, but you know the engine is clean with updated defs.