I recently purchased Game Jackal Pro, and frankly, I think it rocks. Basically, I hate carrying tons of CDs or DvDs around with my laptop for my games (my laptop is my main machine); they take up space, they get scratched, and I don't really like operating the internal drives in laptops (they always seem flimsy to me).
Game Jackal does a great job of storing game profile information on your machine and creates what amounts to a virtual drive on your machine (it even hijacks your physical drive while running). So far, I've no problems with any of the profiles I create and use. It really makes having multiple game installed and playable very simple. I only had trouble with Diablo II of all the games I have. It will also create a complete copy of the disc on the drive if it has to do so (that might resolve the Diablo II problem, but I've not tried it yet).
If I have on complaint it's that the software upgrades by completely reinstalling itself. So far, it's not been a problem, but I could see it being one in the future.
Overall, super good software!