For the sake of convenience we'd suggest getting a good monitor and adding a tuner card to your PC.
This will also add the ability to record TV straight on your PC, which is very handy. Buying a TV limits you to the tuner onboard, which may mean analog instead of superior digital.
Make sure to get a monitor that will accept computer inputs (VGA and DVI/HDMI) as well as analog ones like AV and S-Video, which will allow you to connect DVD players and the like if you wish. Check out our monitor reviews here.
Of course, buying a TV with an onboard tuner and adding a media centre will allow you to have the best of both worlds. If you go this route, try to get one with an HDMI/DVI input.
Be aware that many TVs with onboard digital tuners won't have a digital output, though.