I personally like AVG free edition.
Free, free updates, paid version if you need more functionality, great antivirus program in my opinion.
Also, for firewall, PC tools Firewall plus. That works for me, also free. Although if you are behind a hardware firewall you may not need to worry about it. The times I've used Mcafee recently, Mcafee seemed to really slow the computer down more than necessary in my opinion.