i also vote for Spybot Search and Destroy. used it since Windows XP.
my windows XP setup before was a combination of both Spybot and Spyware blaster.
for Spybot, i turned off its internet explorer active protection "tea timer" i thought it was an overkill with the pop-up notifications.
spywareblaster is a good preemption for virus/malware that can come from internet browsing. i only stopped using spywareblaster when it detected even the adbrite homepage to be possible malware.
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for my windows 7 setup, i only use avast free edition. so far, there has been no virus/spyware that has entered my system.
**as with everyone, i agree that the best antivirus/antimalware program is always that one that is most updated by the user