I friend of mine has a dual core system and Mcafee running on it. Whenever Mcaffe was running a virus scan, it would take up 50% of the resources. Normally, that's not that big of a deal, but even when ithe virus scan was sitting idle, doing nothing, it would still take up 50%.
I have or had Norton 360 installed on my "single core" system which was 2.6 ghz, but it took 6-7 minutes to startup and settle down. Before, it only took about 2-3 minutes.
Avira has the highest detection rate, but the lowest removal rate. So, if you get a virus, there's only a 50% it'll be able to remove it.
Top Internet Security Suites of 2009
http://www.pcworld.com/article/16561...s_of_2009.html