After some abysmal antivirus products it looks like Norton may have gotten back to it's roots a little with a version that seems pretty lightweight... MS has 90 trials posted in its partnership program so I figured I'd give it a try on one of my machines.
So far it's been pretty much invisible. I'm not too sure I'll pay for it once the trial is up (AVG free has met my needs so far as long as you don't install the linkscanner crap)
Anyways if any of you guys/gals want to try it, here's the link
symantec
Edit************ I tried the antivirus only, not the 360*********