avira anti-virus is the one to get. It is very lightweight and was rated pretty high in terms of finding virusus. Each time it updates (once a day) you get a pop up ad to upgrade but it works great. I honestly don't see any speed hit from it at all.
from av-test.com:
"In terms of pure detection rates in on-demand scanning, a beta version of GDATA's AVK 2009 topped the charts for both 'malware' (measured against 1,164,662 samples) and 'ad- and spyware' (94,291 samples), with Avira's Premium Security Suite 2008 a close runner-up in the former category and F-Secure 2009 placing second in the latter. Secure Computing's Webwasher gateway product, based on the Avira engine with some in-house heuristics, came third in both categories. "
www.free-av.com
http://www.free-av.com/
End of discussion for me. Avira is always at or near the top and is free. It is updated every day -- sometimes twice.








