I don't think it's possible otherwise people would've been playing Halo on the PC long before it was released for the PC. But I did find this link
http://www.dvdwizardpro.com/copygames.html
Not sure if it's legal, but this is what it says:
"Game Copy Pro now includes information on how to play all of your favorite games on you PC, no console, or mod chips needed! You will be able to play PSX, PS2, Dreamcast, even Xbox games straight from your hard drive. We will go even further and show you how to download games online!"
The part about '...how to download games online' sounds fishy.