"To use d the WinTV-HVR-900 for TV with the Windows XP Media Center application a Media Center certified DVD or MPEG-2 software decoder is required. If you are building a Media Center PC, refer Microsoft's web site for a list of Media Center certified DVD decoders. The Windows Media Center application is included with Windows XP Media Center, Windows Vista Ultimate and Windows Vista Home Premium editions only. The enclosed remote control is not MCE certified and does not replace Media Center remote control."
Can you tell the forum what Media Center certified DVD decoder you installed?
Bob
Sound is gone!
My system is Win7 32bit, Hauppage HVR-900 tv tuner, some Realtek sound card on the motherboard.
I use WinTVv6 application to watch tv, and both picture and sound works.
When trying out the built-in Windows Media Center to watch tv, the sound won't work. All other sounds work, including media center menu sounds.
I've tried muting and unmuting the sound mixer (also when media center is running), searched for channels a number of times, and tried altering the TV/
Audio options in media center, but not being able to get it working.
I've also downloaded and installed the media center pluign for my tuner at hauppace.co.uk, without really understanding what difference it made (perhaps to enable recording, which I am not particularly interested in).
I suspect Win Media Center isn't listening in on the correct hardware or something, but i really don't know.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic