I think Avast is better.
I suggest you to install Avast.
I think Avast is the best AV out there, rivals the paid ones.
i'd say got for avg free addition, but since i started on hackforums im considering changing to something more advanced
Mbam (malware bytes - anti malware) is one of my favorites, and yes of course Microsoft security essentials is also very good and uses very little resources. All the big named ones i.e nortan they just make your PC worst in my opinion. Not at all worth the money they ask for it.
Out of the 3 you should go with AVG 2011 one year license and I'll tell you why. The detection rate on AVG ain't that great but it has this useful feature called identity protection. It's behavior based and will give you the option to block malicious malware whether or not it's detected ! Very useful for 'fud' trojans trying to infect you.
I Run a combination of Malwarebytes Antimalware PRO and avast! Pro Antivirus. Im not here to brag about my security.
Avast is the best you're going to get free. But if you're willing to pay, then I suggest ESET Nod 32
I personally use AVG. Never had a problem with it.
I believe Malware-Bytes is a good program, people say it is not an anti-virus. I tell them "It cleared up 755 trojans, 41 registry errors, and removed other stuff". That right there tells you it is not only an anti-virus but an anti-virus that cares.