I need a serious workhorse computer for complex simulations

[Ganjasaurus Rex]

I am running simulations that involve around 6-10 million calculations. My files (10 of them) are each over 500 MBs large (all data and formulas), if that's any indication of the size of the project i'm dealing with. I am currently bogging down a Dell PC with 2.2 Core Duo processor and 2 gigs of RAM. It literally won't run the program in less than one hour.

I have about $6000 in my lab budget for a computer to run this simulation, but i want to make sure i get the most bang for the buck. I priced the following Mac Pro setup at around $6000 (education price).

Mac Pro
Both Bluetooth 2.0+EDR and AirPort Extreme
One 16x SuperDrive
Apple Keyboard and Mighty Mouse - U.S. English
Accessory kit
Two 3.0GHz Quad-Core Intel Xeon
Mac OS X - U.S. English
8GB (4 x 2GB)
750GB 7200-rpm Serial ATA 3Gb/s
ATI Radeon X1900 XT 512MB (2 x dual-link DVI)


Can i beat that system elsewhere for the same price? Please keep in mind that i don't want to use it for daily work... just these, and future, simulations.

TIA