I been a big fan of AVG Free but I had a lot of problems with it. So i’m a proud user of Avira AntiVir, it’s very light weight and works really well. It does take a little long to update but to me that’s not a big deal.
Consistently at or near the top of independent efficacy testers, Avira’s AntiVir remains one of the best freeware security solutions around. Its scans are flexible, allowing the user to fully scan both internal and external hard drives, run a preloaded scan–for rootkits, for example–or customize a scan. The latest version introduces antispyware protections, scanning tech that can crack open "locked" files, improved internal security to prevent AntiVir’s files from being maliciously altered, and one-click threat removal–no more baby-sitting.
What do you use for an Anti-Virus?
Amanda on 
Avira is good for XP not Vista due to it’s scans. It doesn’t perform it’s boot time scan on Vista I have heard. I use ESET Smart Security it blocks a keylogger called iStealer if you have it set up right. It warns you if it is going to connect to the internet.
Yes, ESET is really good anti-virus. The only downfall that it isn’t free, but that’s perfectly understandable. I use to use AVG Free but it kept on giving me issues so I switched to Avira and thats been working perfectly and I run Windows 7. I personally could not use any anti virus software because common sense is always the best protection against that stuff.
But thanks for the comment!