I’ve been using Windows 7 Media Center for quite a while in a VM with content viewed using an XBox 360 as an extender.  However, I’m looking at purchasing one of the Ceton tuner cards and ended up moving the VM to an ASUS AT5ION-I (Atom / ION) based box directly connected to my TV and receiver via HDMI.   I ran into a problem where audio would periodically loop and cause playback to stop with an error.  After searching various boards it looks like there is a problem when menu sounds are used with a Dolby Digital setup that also transmits audio and video via HDMI.  To work around the problem you can either disable Dolby Digital audio, disable menu sounds (Settings -> General -> Visual and Sound Effects -> Play sounds when navigating Windows Media Center), or disable “Allow applications to take exclusive control of this device” in the sound control panel (advanced tab).  There are several posts going back over a year on this issue on technet, but it doesn’t appear Microsoft has provided a true fix yet.