I don't tend to visit seedy sights, but I have used Microsoft Security Suite for a few years on one of my computers and never had any issues - except one, so worth mentioning.
The laptop in question just suddenly decided it wouldn't connect to Layo (or any other game) through a company firewall and it took me ages to track the block down to the MS Security Suite. Once I disabled it, I got through no problem. And before anyone chips in with two firewalls running (MS Security and the corporate one) being the issue here, I have never, ever had the same problem with any other firewall I have been running interfering with the corporate one. Anyway, that aside, the MS program works really well and is free well, so you can't go too far wrong?