A few people I know run MS Security Essentials and they like it.
I was having a good run with it until 3 of our machines at work got infected. Even after udating signatures and running a full scan it came up with nothing. Luckily malwarebytes is a little better at finding some stuff.
I'm not suggesting that you don't try it, just be aware that most times it seems like you need more than one tool to be safe.