Steam is just done so perfectly. Once you buy it, you don't own it in any physical form, but you have something much better. You own the right to it infinitely. I've even bought games I already own in box form on Steam just for the ease of it. I can download those games on any computer I want through Steam and have them automatically updated without any hassle of digging for patches like in the days of yore.

Sorry about the derail regarding my boner for Steam.