The Power Mac G5's internal design was dictated by the need to cool the super-hot G5 processors. As a result, even though the G5's internal volume was much larger than the Power Mac G4's, it was a step back when it came to storage, offering space for only two drives. Thanks to the Mac Pro's dramatically cooler Intel Xeon processors, Apple's been able to reclaim space from the cooling system and contribute it toward internal storage. And early reports indicate that the Mac Pro is significantly quieter.
Apple certainly knows how to take nice stock product shots. I want to pick one up right away... the dual drive-bay is tempting, but the greatest improvement to me is the increased internal storage. My two 250gb drives have been running out of room on my Dual 2.7, and being able to stick in separate drives for the primary OS & data, Boot Camp, and media storage would be quite a wonder.
