How to play Call of Duty World at War without having to put in the disc?

This is the Games for Windows version, and I don't like how it makes my computer loud when I have the disc in it.

This is possible.

You are legitimately allowed to make backups of your purchased media. Take your Purchased game and do the following:

1. Insert the DISC
2. Move all the files across to your computer
3. Download IMGBurn to turn your Files into an .ISO
4. Download a virtual Mount software like PowerISO etc
5. Attach your .ISO to the virtual mount
6. Load up the game as usual and enter in your Key Code
7. Play.

This does work. Everything is possible.

There is no legitimate way to play or install the disc version of the game without using the game DVD.