If you use limited Windows accounts, only the IP blocking feature works. But I consider that worth the once-a-lifetime fee!

AdAware was one of the few that actually kept malware from operating on the limited side(AdWatch), but I don't trust Lavasoft since they got bought out in January.

When I tested AdAware in my honeypot lab, it would usually block known malware, even if it didn't need privileges to run. It would do this silently, unless you tried to force the issue, and then a warning alert would pop up. Too bad I can't trust it anymore. The RAM issues were challenging on older machines anyway.