Funny you mention Comcast. I have heard of a bunch of folks that have Comcast and use AVG and it porks their email(Comcast email). Most people strip out the AVG and go with Avira out here, or they just use gmail instead of the Comcast email service. I am not a fan of McAfee myself.
I switched from AVG to Avira the other day...
I called my geek friend and told him that my laptop was starting to run slow and askedhim if he wanted to do a little touchup to it, he told me to uninstall AVG and put Avira on to try it.
Avira found 3 viruses and a trojan that AVG missed and the laptop SEEMS to run a little faster. Malware bytes is also installed.