McAfee has been my best choice so far, it doesn't slow down the computer and protects me good enough (I hated norton's computer load even with my P4 2.53Ghz and 1GB Ram it was slowing down my computer).
Yes i agree with nirvana
kaspersky made by russian really the best (y)good protection
maybe is the deisgn of the program not so nice as the other but its best.
all but norton. norton got just blocked by some virus, never removed anything, and is updated way too much and takes too much of your CPU. avg free, that i'm using now, serves me alot better, and is free.