I prefer to mount an image of the game disk. Since I only have two games I play with any frequency, it isn't a problem. Even then, someone sent me the base files I needed to mount for BF2 so I don't need to mount the whole thing. Now I just have to find the same thing for COD4...
I don't play anything online with a no-CD fix. It's too easy for the files to be picked up as a hack, and I like to be able to play without being banned. It's too easy to just make an image and mount it to chance it.