One point to remember is get a digital tuner.
Also you will need a decent antenna unless you are close to a transmitter and the laptop will havee to have Media Center installed.
I use TV Catchup. click here
which has most of the Freeview Channels.
You have to log in and watch a 15-30 sec advert on startup.
The picture is not as good as Media Center but quite acceptable.
My D/L speed is rarely above 1.5 Mb/sec but I rarely suffer buffering.