Anyone have recommendation for the best drive to buy to fill the other slot? Quad will be used primarily for digital photography and HD editing with Final Cut.
The G5's ship with 250GB Maxtor HDD's (check the System Profiler). I just bought a secondary 300GB Maxtor 7200rpm 150-SATA drive for my machine - just like the one that came with it, only slightly larger.
My way of looking at it is that you can't go wrong with something already trailed and tested!