I bought a "supposed new the orange box game" that turned out to be used. Thankfully, I got a refund. Can I buy a steam copy of the orange box, and install it from the used retail disk, without it asking me for a cd key, and without downloading the full game (excluding updates), if I already bought it on steam? Just to use the disk as a faster installation method.
Valve and other developers release updates for their games pretty regularly. Valve themselves are going through a process of changing the format of all the games available on the Steam platform. Lastly, Steam has got to be on-line to install any games.
You can try the disk but I think Steam will simply download the game with the updates already installed.