I'm amazed that people put up with the effects of McAfee!
Several folks locally have asked me to look at their computers, after mentioning speed problems with "new" machines. They all had McAfee "free" with the machine, then paid to renew it after the free month.
They now all have ZoneAlarm, AVG, Spywareblaster, and AdAware.
I've never had any speed problems with AVG - stuff opens pretty fast.