building a okay game pc with a dual processor workstation board

[bjams87]

i have a HP Compaq xw8400 Motherboard Dual Processor CPU 442028-001 it has 2 Intel Xeon L5420 2.5GHz/12M/1333 Quad-Core LGA771 SLBBR CPU's with Micron/HP 16GB (8x 2GB) ECC Fully Buffered DDR2 PC-5300 Memory - 398707-051 would i be able to put that back in a tower and with a better GPU and put windows 7 on it for games.....lighting took my good computer lolz

any advice for Graphics card and then hard drive set up would real welcome