Free antivirus for Windows 7?

[Pocketa]

I just got Windows 7, and I have no antivirus. I've never used one.

What kind should I get that's free? My mom doesn't want to buy one.

[Innis Cabal]

Avast! is good. Probably one of the best you can get.

[Force]

I use AVG free. It works.

[Anuan]

Avast! is really good, and if you ever have a problem it can't fix, download the trial of MalwareByte's AntiMalware.

[Starscream]

I also use Avast with 7. Works good.

[Zeb The Troll]

We use AVG and haven't had any trouble.