A little while ago I talked about Tuner free for MCE from MillieSoft. This allows you to watch a whole load of channels on your Media Center PC without having a tune card installed. You can even get this contemt streamed out to XBOX360s as it supports extenders.
Theres been a whole load of updates been done recently, including the integration of the MSN video sources that came back on line in the UK earlier this year.
Its a really cool program. You can install from here.