Microsoft Security Essentials seems to be a fine, lightweight AV solution, and it's getting a lot of positive reviews. Microsoft is explicitly positioning it as a solution for home PCs, but are there any reasons not to run it on a server? We use McAfee Total Protection Service on our desktops, but it's not entirely compatible with the server, and in any event the software firewall and link protection features aren't necessary on the server anyway. We have a single SBS 2008 server running things, so I want to make sure it has decent protection. Is MSE the answer?
if you care about licensing, then - no.
Use. You may install and use any number of copies of the software on your devices in your household for use by people who reside there or for use in your home-based small business.
There is Microsoft OneCare for Servers, it's a paid option.