Most programs that will run on Windows Server 2003 or Windows XP will be fine, but it's not supported, and in the general case not recommended. In the case of PVR software, you will need to get your tuner working in Windows Home Server. You'll need to allocate storage for recordings, too. Probably you will want to record to a location outside of your server's shares (and to a disk not in the storage pool) for performance reasons, then you'll have to move data into the shares if you need it there.
In the home theater realm of applications, the recommendation is to run a "two box" system, where you have a home theater PC that deals with display, transcoding, etc., and that PC uses your home server as additional network storage.
I'm not on the WHS team, I just post a lot. :)
