I am running winxp pro sp3 on a dual core pentium @ 2.8 gig with 2 gig ram.
Comodo version 6.2.282872.2847
Avast free program version 8.0.1489, virus definition 130727-0.
I configured Comodo to check for updates every 30 days - some days I see a pop-up to update 2, 3 or even 4 times during the day. From my perspective, this is quite annoying.