Hi Lisa,
I'm dual-booting since this is my home personal network. I'm originally a Windows user and have been easing into the transition to OS X. I have an SBS 2003 server setup on the Windows side. My interest in using OS X joined to my active directory is primarily to safeguard my files and ease the accessibility to my LAN folders. This is useful for the Plex media server i'm running off a Mac mini (movie files are on the SBS box), as well as keeping my kids out of trouble when they upload their photos (and ensuring what they upload off their Macs gets backed up on the SBS server).
As for VM Ware, i'm using Snow Leopard server (developer version) running on VM ware on the SBS server. I suspect that's a big no-no, but the mac mini alternative has been eliminated since it has Lion on it and I can't get the **** thing to work.
As an aside, I reformatted the OSX partitions last night to go back to Snow Leopard. The thing joined the AD and OD domains so easily I couldn't believe my eyes. I'll stay on SL until I hear much better things about Lion. For now, I'll stay far far away.