because they are prof rendering cards, they have things enabled for those kinds of apps such as line AA, the firegl cards are the same chip used for retail market, they just use a diffrent bios and normaly small changes to pcb like a moved resistor or the like.
most real pro's prefer something like the 3dlabs wildcat cards tho.
as to xeon, why xeon, why not opteron, amd will have quadcores out soon, dual quads=4x4
should be a better preformer then intels offerings if operon vs xeons of the past is any indocation.