Malwarebytes is a great scanner, but it's real-time protection could use some work. I have it detect false-positives all the time on customer's machines. I've actually stopped recommending the paid version until it gets a little more polished.
I use it for just that: a scanner. For real-time protection I suggest finding other solutions. MBam is no doubt a damn good program though. I've used it to bust some ugly viruses and malware before and it ran through them like a train.