The one thing I'm not sure about is video playback.  Would something like MythTV give me what I'm looking for?  If I installed it on the server and HTPC would I be able to control them via the laptops?  Does it integrate well with MH?  Are there any Windows based programs that would allow web based HTPC control and could integrate with MH?

MythTV has a network control protocol. It should be really easy to configure MH to control Mythtv via TCPIP. You just open a TCP socket to the port and issue commands. You can jump to any screen / menu in mythtv as well as retrieve show names, play, pause, ff, rw, stop etc all via commands. Even has keypress commands you can send.

- James