You would need a fairly powerful machine, good size HDD and a TV card connected to a decent aerial. If you wanted to put anything onto DVD you would obviously need a burner. You may find the following links helpful, the last is an Ask (Jeeves) search.
If you just want to get it on your hard drive then you can do as Johndrew says If you are thinking of then putting it on dvd you will need further software as it is is not all that straightforward therefore go for the recorder as terry says
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