If you like the idea of watching TV on your laptop, but your budget doesn't stretch to a Media Center machine, opting for an external TV card is a viable option. The 320U is a hybrid tuner, so you can watch standard terrestrial channels, as well as digital (Freeview) ones.
The tuner plugs into your laptop using USB and there is a standard aerial socket on the other end, either for the supplied mini-aerial or for plugging straight into your roof aerial for a better reception.
The software isn't the most friendly we've come across, as you need to manually install drivers. Even then we found it erratic at best, with the software refusing to set up the tuner in digital mode, only analogue.
There may be a good TV tuner here, but Kworld has done such a bad job of the software that it's impossible to recommend it.