Since you dont need ecc which is the main difference between an I7 and the xeon you would be better off useing an I7. In particular the I7 930 which just came out supports 2.8 ghz 8m cache and a 4.8GTs QPI will perform about on par with the W3565 at a quarter the price. Also what else do you need for this build Hard drive, graphics card, power supply, OS. Do you need any of those?
Depending on what you need I think the I7 930 which goes for 300 on a nice x58 motherboard overclocked to say 3.4 to 3.8ghz will give you all the performance you need for what you are doing.