Spent ages reseqarching this stuff on sites like PC advisor (a free Vs paid for AV argument there is the same as a able debate here), and decided that its very hard to know what tests to trust, and that many dont actually test what they are supposed to. In order to fully understand them you have to be very knowledgeable indeed, which means you need the aptitude and the inclination to educate yourself very thoroughly. Thats not me. If you are like me, therefore, the best i think you can do is get one you liek the price of and find easy to use - you need to be a bit philosophical here and remember that any AV is fallible, and that much is down to user error. Make sure you have a firewall and some anti spyware too of course, aswell as AV, but they may be in the same package depending waht you get.
i had avg and zone alarm a while back, and avg stopped updating automatically after an update, so i got shot. Ive had to change back to it now tho, and have only had it on since last night. when i got up today it would not access the net, so i had to update manually agian. this is really irritating, so may have to go for something else again unless i t improves, and could be tempted by kaspersky. however, future upgrades of kaspersky would presumably be obtained via download, so after initially buying the cd, you wouldnt have a useful cd after the initial version upgrade...?