There are several good anti-spyware solutions...
A nice, helpful post. Thanks. I thought I'd add this, as some may be looking for a suggested routine in using the mentioned tools.
My browser of choice is Firefox 2.0, with NoScript and Adblock Plus (with both the FiltersetG and dutchblock lists) installed as extensions.
With that in mind then, here's my normal routine:
My choice for a firewall is Zone Alarm Free (note the version number from my signature - last best version in my opinion).
I run a standard scan on avast once a month (some will argue that you run it more often).
Windows Defender runs as active resident.
SpywareBlaster runs as a passive resident.
Spybot and Ad-Aware are run as often as the definitions update. (I make it part of my morning routine to check them along with SpywareBlaster for updates.)
Weekly, I clean out the cache and cookies on Firefox, and I run Disk Cleanup.
Once a month, I run Scan Disk and then I defrag the hard drive.
Once a month I run Trend Micro HouseCall, just as an added touch.
After the monthly routine, I then backup files and settings using SyncBack to a flash drive which is locked away in the fire safe. (That frequency works fine for me, others will want to backup more often.)
Understanding, that I don't run through the internet barefooted, with this layered approach, I haven't had a problem for as long as I can remember.
I'm sure that all of the products you've mention work equally well, this is just my set-up.
It's the importance of establishing a routine that I wanted to zero in on.