uhhh, steam is amazing. Your account can be uploaded on any computer and it has all of the games on it permanently. One install and you can take your games anywhere, just login in and download. Not worrying about CDs getting scratched because after the first install you don't need them for play.

I got steam for Half-Life 2, and get most of my games from them. It is excellent and non-intrusive, I think the people who hate it should try it and realize how awesome it is.