You can buy it directly from Blizzard, I think it's only $10? If not look for a box at Gamestop, it's usually $10 there.
OK, Here's the link, it's $15 for the whole set:
Thanks very much for that I'm in the uk I can still buy and download it right?
I used to love that game on my old Gateway! Where the hell would I find it now lol?