500GB WD Caviar Blue as my main HDD in my build (contains system files, games, apps etc.), and a 1TB external hard drive for my music, and large files such as HD films.
I have about 15 old IDE drives about that I've got over time from computers that friends and family have been getting rid of because they've been getting new ones, they couldn't sell them so they let me salvage them. Most of the hard drives are 20gb and theres a couple of 40gb, some don't work. I'm going to sell them all.