Drew - Strange. The card is definitely connected to the motherboard by 2 power cables.
Tim -- I'm just trying to keep things on topic! If we're talking about Macs, we don't need random Windows stuff in the mix. Everyone already knows that Windows boxes are more versatile in terms of hardware configurations, but they don't run Mac OS X or Final Cut.
Here is a clean option for adding up to 4 additional 2.5" drives to a Mac Pro:
http://www.transintl.com/store/category.cfm?Category=2799

It comes with a motherboard to 4 drive power adapter and a bunch of SATA cables. Looks like a good solution, but perhaps overkill for what I need (and, all available motherboard power is taken up by my video card).
I ordered one of these, instead:
http://www.xpcgear.com/scythe-2-5-to-5-25-bay-rafter.html

For $8.95 + shipping, it will allow the mounting of 3 x 2.5" drives in a single 5.25" bay. I'd leave the center space free for airflow and forgo the fan.