The place I worked for (software testing facility) didn't want to pay for Norton (it was more at the time) so we all used McAfee. I finally bought my own copy of Norton the 2nd time a virus brought almost the entire place to a screaming halt . . . and McAfee couldn't find it - updated or not! They continued to use McAfee & I'd notify people that someone was "sharing" a virus over the network that Norton found. After a couple years, they finally broke down & bought the corporate version.
DF's PC came with McAfee, but when he bought a cheap no-name scanner the software wouldn't install with McAfee. He's now using Norton also.
I used to have McAffee until it caused so much trouble on my computer and it missed several viruses while I was in college. I am now on Norton and much happier.
I have used AVG for the last couple of years and loved it. This PC came w/ Norton's and 3 months of free updates and it's O.K. but I really like AVG better so when the 3 months is up I'm switching back.