Analog tv cards work fine, digital ones don’t without bda support.
More: http://www.hauppauge.co.uk/board/showthread.php?t=14850
It isn’t because of the drivers. Atleast if your tv card has drivers available that work in vista sp1. It’s because server 2008 doesn’t have support for bda devices. I have terratec usb dvb-t stick. Installed usb over ethernet software and tried terratec home cinema (viewing software) in virtual machine, xp and vista and it worked. So drivers work in this case just fine.