Spybot when running seems to be my heaviest user at 50% CPU while scanning. After it stops scanning I'm back in sigle digits with all normal background programs going.
I downloaded the paid version of SpyBlaster and quit using it. I rely solely on AVG (it has everything) and have had no problem with it. I have 4GB Ram XPS 720 on broadband. Sorry for your dial-up.
A new thing AVG does is it puts a nice green checkmark beside safe Google hits you might want to open to indicate they are safe.