Since I got this computer, I have not been able to use the TV tuner that came with it in Media Center (or Media Jukebox). I thought I understood why, but now I can not remember
Maybe there is something special about the hardware, or its just Sony did not have WDM driver. Usually a WDM driver would show up in Device Manager, under "Sound, video and game controllers". I see there an entry called "Sony MPEG2 Encoder Board (WDM)". It probably refer to the TV board. But there seems not a WDM Video Capture driver.
Basically, MC TV relies on Microsoft DirectShow to enumerate all video capture drivers available. If its there, MC can use it, otherwise it can't.