I have never been impressed with the majority of anti-virus programs out there. Used to use Avast free, and work great, until i saw Kaspersky Pure, this is the First anti-Virus i have ever bought, and i highly recommend it to all my clients that come shopping.
Otherwise, dont go AVG, not that great, if you looking for a free AV go AVAST, works great.
Go Microsoft Security Essentials, cause no matter what you choose, you will be 100% safe for casual online gaming and websurfing. If you want to check "dangerous" websites, then you NEED a paid solution
I recommend MSE(Microsoft Security Essentials) for the average computer user because all of the definition updates and virus protection updates go directly through windows update. So the average user who doesnt know how to update the antivirus or setup an automated update service its great.
Just use the Microsoft one it's perfectly fine. But you should add a few more things to really protect yourself as well like Malwarebytes free version as well as superantispyware. On top of that stop using any other browser other than google chrome it's the best browser, fast, secure, and will protect you from harmful sites.