Everyone is going to have their own opinion of what is best. To be honest I have seen norton working fine on one system and crap on another, same with Mcafee and symantec. There just seems so much variance.
My advise is suck it an see. If you don't want to pay then AVG, else I prefer symantec for vista and McAfee for XP.
I've always preffered AVG Anti-Virus and AVG Anti-Spyware, tagged along with Windows Defender and McAfee VirusScan and SpywareScan Enterprise Edition.
I've got the trio installed on computer and laptop, and they seem to do the job. AVG does pick up a lot of spyware, I must say. It must be the sites that I visit!
As oneman said, everyone has their own opinion. As he also said, just have a look at what available, free for starters and if you don't like it you may switch over to the paid option which obviously enables greater options in regards to the VirusScan/Spyware software.