If you need the Stereo 3D, I'd say go for it, or if you have software that is qualified for the Mac K5000.
Otherwise your'e just wasting money on an old piece of hardware. Other than the 3D port, none of the other Quadro features work with the Mac drivers, unless this card is supported ECC Ram in the OS X nVidia control panel.
Quadro cards are not any faster than there Geforce counterparts in software that relies on optimized Quadro drivers.
Somewhere around here I linked the OS X version of SpecViewerPerf, and it tells no lies, Geforce hardware is just as fast in Pro apps, because nVidia never optimized the OS X drivers for the Quadro line.