I never had any problems with Norton. To me, it's the best protection for your computer. No slow downs at all. LiveUpdates keep your PC protected all the time and has a nice, clean interface. Get 2005 Norton Security. COmes with Antivirus, Firewall, Ad Blocker, Parental and Spam control, etc, etc.
That is what I am running now on my new PC. Excellent product.
*Fact: Microsoft Window's Blue Screen of Death vs Computerforums.org's White Screen of Death. Which is worse?