I try to stay away from McAfee, Norton and now ZoneAlarm like the plague. Their footprints are large, eating up memory, and they tend to be way too agressive when it comes to blocking incoming and exiting computer traffic.
Everyone, please listen to Al. Do not buy McAfee, do not buy Symantec/Norton. ZoneAlarm started the software firewall business along with Tiny Firewall. They used to be pretty good. But, I agree now.
I have no idea how McAfee and Norton stay in business. But, mainly it is because of their name. At least McAfee can be uninstalled. Good luck with Norton/Symantec.