For the record I build my own, and it is cheaper but I do have to troubleshoot hardware issues... if you are not capable of or willing to do that then a BOXX is nearly a perfect choice for anybody working in CG.
I have more knowledge and time than money at this point so I don't have one -- but if I had less time and more money than the BOXX would be my system of choice with a Mac Pro being the alternate choice.
Best,
Jason.