I've used Malwarebytes.
My personal favorite is AVAST. It updates on it's own, runs at all times, so it stops viruses before they happen, & it doesn't give you ass if you want to turn it off when you want to play games. Also, far less of those irritating pop-ups. I run it with Threatfire as a firewal, then I double the security with McAfee Site Adviso, which is the ONLY McAfee program I would ever recommend to anyone. All of this stuff is free at http://download.cnet.com/windows/security-software/?tag=rb_content;contentNav
I can say that Avast is better than AVG Free, Spybot, Ad-Aware, McAfee, Norton, Avira, & Malwarebytes, since I've used them all. I've heard some bad things about ZoneAlarm, so I never risked trying it.
My personal favorite is AVAST. It updates on it's own, runs at all times, so it stops viruses before they happen, & it doesn't give you ass if you want to turn it off when you want to play games. Also, far less of those irritating pop-ups. I run it with Threatfire as a firewal, then I double the security with McAfee Site Adviso, which is the ONLY McAfee program I would ever recommend to anyone. All of this stuff is free at http://download.cnet.com/windows/security-software/?tag=rb_content;contentNav
I can say that Avast is better than AVG Free, Spybot, Ad-Aware, McAfee, Norton, Avira, & Malwarebytes, since I've used them all. I've heard some bad things about ZoneAlarm, so I never risked trying it.