I've been having trouble tuning my 8920 dvb-s2 card into the recently available channel 4 HD in windows 7 media centre.
This is a common problem in 7mc, not just your card, but it seems until microsoft release a patch (if they ever will) then it is upto the hardware vendors to fix it.
I read good things about this company before buying my card, so I am hopeful you can sort it soon.
here are a couple of forum links to illustrate the problem. So far I have read that hauppage and blackgold have released driver updates/patches.
http://www.mediacenterhouse.com/forum/Thread-dvb-s-card?page=2
http://thegreenbutton.com/forums/t/99778.aspx
I look forward to a speedy reply. I will keep looking around the net for a fix, if I find one I'll update in this thread.