Go to gamecopyworld.com and search for the game's name there. Look at the list of offerings for something called a "mini image or no-cd patch or such". You'll need a program like alcohol120%, or daemon tools to run a mini image, or the patch or crack you just copy a file over the original in the game directory, which makes the game skip the cd check.
The mini image is a tiny image of the data on the game cd which daemon tools mounts onto a fake (virtual) cd drive, tricking the game into seeing a game cd, which isn't there. An ISO is an actual full copy of the game doing the same thing. The mini image is just the bits important to the trickery, and way smaller. Email me if you need more help.
A no-cd crack or patch is easiest! Daemon tools has a free version which works for all but the bleeding edge protections out there. You'll have to turn on the protection emulators for certain games.
If you own the cd, this IS LEGAL!