I guess I'm a little puzzled by one thing... why did you get an Xserve instead of a Mac Pro, again? They're identical. Both of them use software RAID (not hardware) and they use the same error-correcting RAM so there really isn't a reliability case to be made for one over the other. I'm guessing the Xserve was cheaper? (Taking a peek at "buy it now" prices on eBay that seems like a workable theory...)

On the subject of sound devices, I was pleased when I found a dinky little USB audio device in the garbage the other day. It was labeled "Plantronics" and was apparently designed to be used to adapt their analog phone headsets to computer use. Seems to work like a champ with OS X and Linux, complete with full volume controls and enough output oomph to drive a set of headphones. I love free stuff.