And Microsoft catches things that Spybot and Ad-Aware misses! The problem with all these is that you really need to use them all in order to clean everything. Why can't someone put all of them together?
Make yourself a schedule and put them together yourself. Run one scan per day before you shut your computer off, or go to bed, or go home, or whatever.You don't have to sit there and watch it.This is the one I made for my wifes computer at work, it seems to work pretty well.
Monday update and run AVG antivirus
Tuesday update and run Adaware
Wednesday update and run Spybot Search and Destroy, you might as well update Spyware blaster while your at it since it runs in the background in conjunction with Spybot S&D
Thursday Run CCleaner or an equivilant disk cleanup/registry cleaning utility.
Friday Defrag
Note all the above utilitys are free or already on your computer ie.Defrag,Windows also comes with a disk cleanup utility but it doesn't work anywhere near as good as CCleaner.There are many more Microsoft,Yahoo,AOL all have thier own but the ones I've mentioned all work on just about anything from a crusty old P2 to the latest P4s.
Yep, you need more than one to catch all the garbage out there. FWIW, these two online scanners also look for spyware:
Panda Online Scan
Trend Micro Online Scan