neither ..... norton always has and still is a resource HOG! , as for kaspersky i have run it on win7 beta and rc1 ... but i was NOT impressed at all (also slow and chunky with resources). i'd suggest AVG or Avast
AVG is starting (actually has already started) following in Symantec's footsteps from back in 2004/2005 at the height of resource usage issues which plagued their consumer products for years. I'm still not sure why they didn't use the same approach as their corporate products which were much better about their resource footprint. They would have kept a lot of customers doing that, but i'm glad Symantec has learned. It's just too bad that Grisoft is going to have to do the same.