I went from a heavy package to a lighter package. I converted to Kaspersky Personal (from Mcafee). It uses two processes and hovers in the 11- 20 meg range idleing. Kav.exe is idling @ 679kb and peaked @ 11 megs/ Kavsvc.exe is idling @ 9.3 megs and peaked @28.1 megs.
The interface is very simple. Seems like everytime I update it manually it has a new definition for me. I also have it set to automatic. Sometimes the server is real slow though, but unlike my last pig of a security package it seems stable. I coupled it with Outpost and I feel as I test it out, I might just keep it.
Right before my last format, I took out Mcafee and installed Norton which came with my motherboard. Yikes that thing is really bloated, I can see why you want it out. I would see what scanner you like that is a good product. All of them offer a trial that you can try out and see how it suits your needs. I just happen to find my current scanner, meeting mine for now. Fast and light on it's feet. I have read horror stories about the support though.
One other virus scanner I liked was Trend, the firewall part is not as good though. If your going after just the scanner it would be a great pick.
If you want a good suite, I installed Panda Platinum on a machine and it seems on par with the other quality suites. Not as heavy as Mcafee or Norton. I am leery of suites latley. If you get hit, the whole suite goes down. I would recommend an independant approach. Though, it is nice having everything in one spot.