DON'T USE "Microsoft Security Essentials" as your Anti Virus - it is the worst AV I've ever used.
I'm not right up with computers, but, I have found Microsoft Security Essentials great. It doesn't slow your computer like the other ones do and it just sits around in the background, has found a few trojens and removed them. I use that combined with spybot and haven't had any dramas with viruses or spyware.
What was it you didn't like about it Nino?
My problems started with AVG Free. One of their updates stuffed up my video driver and the PC would not boot past the Windows logo. It was a known problem that created issues for Windows users. Some could be repaired, but mine was too far gone. So I re installed windows, but I chose not to install AVG, but try MSE. After a week, I noticed problems with MSE going offline (icon turned yellow) and updates were not working. Scheduled scans stopped running. I forced a "full scan"" of my PC and it took 50 seconds to complete. I uninstalled and re installed. Same problem.
I installed Avira Freet and on its first scan, it found 23 problems. I checked each one (for false positives), and they were indeed malicious. It updates as it should and works fine.
I administer 2500 PC's at my place of employment, and we used Sophos. Brilliant product. We are thinking of going Microsoft Forefront, and from what I've heard, it is a poor AV solution.