I currently have Norton and have used McAffe.
As far as Virus protection, both do a good job. As far as working well with other products, I believe Norton to be a bit better.
Both products offer free DAT file updating.... to an extent. At some future point, a software upgrade is necessary to take advantage of new features. With Norton, you can get a subscription for around $29 a year. This gives you both software and DAT file upgrades. I believe McAffe has a similar program.
If you really think about it, $29 or so a year is cheap insurance to protect your computer. All it takes is one bad viral infection and kiss your data goodbye. Plus, quite a few viruses find a nice way of propagating themselves via your email address book. This tends to get your friends and relatives upset.
Terry