What's wrong with the standard Windows 7 Media Centre application -- it works with a lot of TV cards without you even having to install the manufacturers drivers either. It will also download the TV guide as well. I'm using a Hauppage TV card.
The only drawback of using the Windows 7 Media Centre is that if yoiu need to use say the Composite feature (AV in) then you will need a remote but for normal TV viewing it's fine - you don't need a remote.
If you have a SKY TV subscription in the UK you can also watch the SKY channels like SKY SPORTS etc.
For the US I'm sure equivalent subscription TV is also watchable via Windows Media Centre too.