I'm possibly in the market for a DVB-T stick for Vista Ultimate as well; so I'll add a bump to this thread, too.
Adam
I'd say at this point you might just want to give Pinnacle support an email and get them to state in writing that it does not have the problem that you describe; then at least if you order it, you should easily be able to return it if it does end up being a problem.
$0.02,
I don't know if this is of any help, but I'll toss in my two cents worth as well.
I'm running VMC with a pair of Pinnacle dual DVB-T cards (yes, four simultaneous channels, very greedy, I know!) which are allegedly not VMC compatible. However, there are drivers for them on the Pinnacle website which seem to work fine and I don't get any incompatibility issues from them. Or at least I've not seen anything to suggest that they give me problems.
I'd suggest going to the Pinnacle website (http://www.pinnaclesys.com) and looking for the Vista drivers.