Doom 3 with No CD

I recently bought Doom 3 for about $20 at MicroCenter. I read that there were problems if you had CD emulators on your computer, even to the point that the program would not run unless you uninstalled the emulator. Anyway, I am using Virtual DAEMON 3.47 and it seems to work without a problem. I even found a tiny ISO of the game CD so I even play using the program.

Obviously, I bought the game, and I really oppose stealing games. I used to grab a few games out of newsgroups a few years ago but it's just not worth the risk to my PC, not to mention the legality of it. That being said, I do not want to use the CD every time I want to play a game. What if I scratch it? What if I lose it? Programs like DAEMON make it easy--just rip an ISO, copy it to your hard drive, then mount it. Takes up 650MB sometimes but that's not much space, and can be cheap if you don't install the entire game (run movies from CD, as an example).

I like Valve's way of doing things--validate the user over the Internet. Once you validate your game you can play without the CD at any time.