I have to fight myself every time they have one of those sales on Steam.   For example, this weekend Braid is $5.   How do I turn it down?   

It is the best way to buy PC, hard drives are so cheap and there are no disks or CD keys to lose.

Console games are another story.   Hard drives are limited in size and when upgrading one risks losing all of his data.    Too scary for me when I can get a disk and sell it off when I am sick of it.