I inherited a client who has a Winows Vista "server" installed by a rather inept previous IT consultant. He babysat it almost every day as their "server" serving file shares and printers and a couple of apps across the net to mainly Windows XP machines. No domains, all peer to peer file sharing. They need to move forward with an upgrade and I'd like to get them on Windows Server 2008 for various reasons (like an AD and some centralized management among other things). They have a TON of data on the "server" today. I was wondering - can I do some sort of Vista -> Server migration or do I have to reinstall from bare hard drive?

There is no supported path to upgrade from Vista to 2008. This is generally the case for all versions. You do not have the ability to upgrade workstation class OSs to Server editions.Visit: anITKB.com, an IT Knowledge Base.