If you buy a cheap USB video grabber you can take a composite output signal (ie yellow, white/black, and red plugs) from your Freeview or Freesat box and feed it into a computer via the grabber's USB plug. To view it you need some sort of video editor software that accepts the signal as input - there's plenty of free ones.
Obviously you need a dish in place, or a decent aerial of some description for the Freeview box.
We don't have a satellite dish for the main home TV, but I've got a cheap Aldi portable sat dish and receiver attached to my conservatory, which feeds a signal into my PC via a video grabber if I want telly on the computer. This means I can now watch 937 different channels of men in turbans chanting whenever I want.
Yes - a plug in USB tuner & Windows Media Centre - which is better than most of the freebie TV programs that usually come with the tuners.
You need just as good an aerial as you do for any other telly though, so you can't compromise on that. I have a 12v powered Avtex aerial with built in signal booster - forgotten the model number off hand, but it's their standard portable one. Again, the ones that come with the tuner are only any good in very strong signal areas.