There is a handy program called Virtual CD which will do exactly that. Or if you have a copy of Alcohol 120% that does it too. Depends on how much you want to pay, have a look around and see if theres any freeware if not.
Also Clone CD will do it to....how it works is that the program make a copy of the game and saves it to your HD then usually during the install process it make a virtual CD drive and then you just load the image into the virtual CD and your computer and the game thinks that the CD is in the drive .....just make sure that you own the game and that is within its license agreement to make a copy of the game or program Clone CD give it a try well worth the money
What they haven't explained here (and looking at the fact ur new) is that you have to rip the image of the cd first. There are two typical file types to use: .iso files .bin and .cue files I find that they are fairly much the same except when ripping cd's that have music tracks on as well its best to use .bin and .cue files. There are a number of programs available, such as mentioned, Alcohol 120%, Clone CD, Blindwrite Suite, and various other programs you could google for. I personally use a combination of Blindwrite and Daemon Tools, which creates a virtual drive to mount these cd image onto, which will appear in "My Computer". Then just use it like a normal cd or dvd. Be careful though, as this can quickly eat up hdd space like a fat man in an "all-you-can-eat" buffet. I used to have a link to a good site which had another forum you could trawl through for advise. Will have a look later.
Also, be aware that some game manufacturers are setting up copy protection that won't let you do this, whether or not you have the actual game cd. Hell, some of them check to see if the virtual software is even installed on your computer and refuses to run. Is it wrong? Yeah, I think it is. Can you do anything about it? Nope.