Well, if money's no object, than I'd go with watercooling and some of these
nifty innovatek water-cooled rubber HDD mounts. Just check and make sure you can get the right waterblock mounts for the Xeon CPU sockets.
Also, I don't know which Cheetah drives you have, but the 15K.3 Cheetahs are supposed to be respectably quieter and much cooler than their predecessors. Again, if money's no object...
I'm willing to bet you could do better than the components Swiftech has chosen to include with the Q-Power, but it would take time to research, and wouldn't be a "plug-and-play" solution. And the integrated heatsink on the back of the Q-Power is pretty nice.