You would certainly be advised by any number of people here to first "Dump"! McAFee once and for all as the worst of the lot. No one has a good word for it. Norton is also seeing a bad rep as a bloated software.
AVG has been a champ here for some time with the latest 8.0 version seeing some rather interesting improvements especially for gamers running into problems with antivirus being active. The latest build now sees the Ewido antispyware protection added in along with antiroot kit protection by Grisoft. The optional IE toolbar for the free version includes a degree of popup protection as well as an antiphising filter of it's own.
Some others are Nod32, Win AntiVIR, Clam, Avast to consider as opposed to ... McAFee!
You can try out the free edition of AVG at
http://free.avg.com/ww.download?prd=afe