Thanks for all the advice, I am going to purchase a Pioneer DVR-109 for $97.99 from OWC (unless anyone knows of a better option).

I was just wondering if it is okay to swap out the combo drive on my MDD g4, I see no reason to have a combo drive and a superdrive, I figured I would drop the combo into my g3 B&W and stick with just a superdrive in my g4 MDD. Any advice? Is it okay to place the superdrive in the top slot? Thanks.