I am using the free edition of avast. It is great and can able to control most of the viruses. Try and let me know how it works
I would go for AVG for friendliness. However NOD32 is perfectly functional. There really is no point paying out for Norton, or McAffee (We'll skin Norton and add some useless registration stuff) anymore because they are no longer good value for money and hog the system.
I use Anti-Vir (from www.free-av.com) - I had to stop using AVG because I was having problems with it on some of my older systems. Anti-Vir seems to run faster than AVG, and it has done the job so far (I scan with other AV programs over the network ocassionally because I'm paranoid). Really these days I think it's down to personal preference more than anything else.