There's little problem that I've ever heard playing HD Video on the CoreDuos.http://www.macworld.com/2006/03/firstlooks/minifinal/index.php said:I was even more encouraged by the HD test results. HD played back great on the Core Duo mini, and just as well on the big screen (after figuring out the configuration for my older set). When the machine is pushed, the fan kicks up a notch or two, but never gets truly annoying. In my living room, sitting about eight feet away, I couldn’t ever hear it if there was any sound at all from the TV.
There's less Success when playing HD with a CoreSolo (which I have hooked up at home) and ArsTechnica has a good breakdown here:
Mac mini (Core Solo): Page 3
EDIT: I just realized that the MacWorld MacMini review I quoted is from April 2006! Wow. 17 months ago. The Mini really is LONG in the tooth -- maybe all those rumours of Apple abandoning it are true.