spybot (no teatimer)
Useless in my opinion. Definitions not up-to-date, poor detection.
Definitions are updated weekly, usually on Wednesday mornings. Version 2 has been in beta for well over a year, however. Weekly, I've ran SpyBot Search & Destroy scans after updating, MalwareBytes Free, and SuperAntiSpyware Free. None has ever found anything.
If anything, I'd say that Avast (and safe browsing) are keeping things clean. Keeping the OS and all software up to date can be a major task, but is necessary.