Lol not hard to do at all.
Just download Daemon Tools and install:
http://www.disc-tools.com/download/daemon
EDIT: Use Daemon Tools Lite, it's free. No need to buy it.
Download ImgBurn and install:
http://www.imgburn.com/
Then load up imgburn with the desired game in the drive, choose the option to create an image file fromd disc, tell it where to put it, and wait. It'll create a .iso file (or some other file that's a CD/DVD image, not sure what extension it defaults to, shouldn't matter).
Then with daemon tools right click on the icon in your tool tray, then under Virtual Devices, Device 0 (which should also have a drive letter assigned to it, if not you might have to set it in the device preferences option), and mount image. Point it at the file you just created, and voila, you have a virtual drive with a CD image mounted.
You can mount and unmount as necessary, or create multiple devices each with a specific game if you have few enough games you want to do this with.