Dell Precision Workstation T7400 - 64bit
YES
Quad Core Intel® Xeon® Processor E5405 (2.00GHz,2X6M L2,1333)
no need for Quad core, save the money and get a faster dual core
Genuine Windows Vista® Business 64 Edition Downgrade, XP 64 Installed
I like XP64, but vista may be okay too
2nd Processor Quad Core Intel® Xeon® Processor E5405 (2.00GHz,2X6M L2,1333) PR20QC
no need for dual quad cores, a waste of money IMHO, get faster dual cores (maybe times two)
Memory 8GB, DDR2 SDRAM FBD Memory, 667MHz, ECC (8 DIMMS) 8G8E6
YES
Graphic Cards 768MB PCIe x16 nVidia Quadro FX 4600, Dual Monitor DVI Capable FX4600
YES
Boot Hard Drive 160GB SATA, 10K RPM Hard Drive with 16MB DataBurst Cache™ 160T16
if you are on a network, no need for large HD, I use an 80GB and it is fine.
You haven't listed monitors, I'd ask for at least one 24" widescreen LCD, if not two 22" to 24" widescreens. After you get rid of the Quad cores you may be able to fit that in your budget. The computer you spec'ed is ~$7000-$8000 US I'd think.