The Xeon is a quad core, and the i7 is too (8 with hyperthreading), but only 1 is being used. The improvement between the i7 and the Xeon is down to clock speed and any caching improvements. Even if all 8 hyperthreads could be used as efficiently as the single thread is being used, it still would not be faster than the GTX480.
The GTX 480 has 480 "CUDA cores", the Quadro has 32. It also has a better clock speed, and GDDR5 ram vs GDDR3 ram. It performs about 7 times better than the Quadro at n = 2000.
Fitting a linear trendline to the GTX480 numbers using Excel gives an R^2 value of 0.9997, which is awesome considering its a n^2 problem!