Re: Best server OS for our needs?
Oh good, I was about to have a batch of kittens if no one mentioned SBS. SBS is fantastic for what you guys need, and as root said, you get everything included with it - AD, File Services, SQL, etc.
The other nice thing is that SBS includes a lot of extras out of the box like VPN support which is bloody fantastic, integrated backup support, and it runs on nearly anything - throw some nice hardware at it and it'll purr. I run 2008, but 2011 has some refinements that make it pretty attractive too. You can do it on your own, but take a look at solutions from OEMs as well, the service contracts from some of them are amazing.