You can either receive TV conventionally (i.e. using radio waves) or via the internet. Both methods have their problems:
To receive TV from your local transmitter, you need either a PCI tuner card or a tuner which plugs into a USB socket. Your laptop probably won't have space for a PCI card, so you'll need one of these:
http://www.tekheads.co.uk/s/product?product=60 8473
However, the problem with using any sort of tuner with a laptop is that, like all conventional TV reception, you require an aerial. If you're very close to a transmitter, the small aerial which normally comes with a USB device might do the job but, in practice, it's likely that you'd need a 'proper' TV aerial (which defeats the portability of a laptop).
You can also receive TV over the internet, using Sopcast (which is similar to Limewire but specifically designed for streamed video). The main problem with this method of reception is that most TV stations generally don't have internet broadcasting rights. So you're restricted to those stations which do broadcast over the internet (e.g. football matches from China) or transmissions which are (illegally) forwarded by individual users of Sopcast. See here:
http://www.theanswerbank.co.uk/Technology/Ques tion551397.html
Chris