Practice
safe hex. That is, update and run your AV and anti-spyware progs often. Be proactive, and don't rely on them to run in the background to keep you safe.
If you're using the old version of Ad-Aware (personal 6.0), it's no longer being updated, and the last reports and reviews I've seen about Ad-Aware 2007 are mixed, suggesting some have experienced as yet unresolved performance problems.
I used to love Ad-Aware 6, but those reviews are the reason I switched to the free version of
SuperAntiSpyware, which appears to work quite well.
Being on the paranoid side, I also use the free version of
Spybot. They had some performance issues when they first released ver. 1.5, but ver. 1.52 seems to have resolved those issues.
I use both. Neither interferes with the other or any other program.
Finally, use good backup. I have a second drive mounted in a
mobile rack, and I use and older version of Norton Ghost to clone my drive immediately after running all my protection programs and before installing any new program. If my drive becomes infected, I can just Ghost back from my last known good condtion. If my main drive fails, the other drive just plugs in and works, and the most it costs is the price of a new backup drive.
When I'm done, I power down and unplug the drive. There's no virus or spyware written that can jump the air gap when your backup drive's unplugged.
I've heard that the newest version of Ghost works differently. I haven't tried it so I can't comment. Some people prefer Acronis True Image, which also clones drives.