There's places like Amazon, Gamespot, (heck, Steam duh!) that allow you to re-DL game files so you can get games back onto new computers/replacement systems as many times as you need to.
It'd be an excellent, and I mean -excellent- idea to ship them file updates as things go along. That way, new players get the latest updated files and old players have an option to DL from the point of purchase rather than overloading the S-E servers. Many games do this if there's bug fixes or the like for conventional non-MMO gaming, and it'd likely save the company pain and strain AND improve patch-day service as well.