Our engineering department is set up with HP xw6600 workstations running WINP7 x64 and SW2009 SP2.1  The machines are outfitted with XEON 5410/5420 CPU's, FX1700 GPU's, 8GB RAM.  We use PDM so modeling takes place on our local machines.

What kind of performance improvements might be accomplished by adding a 2nd CPU at roughly \$250 a piece?  We're still kind of sucking wind after bumping our OS and RAM and aren't quite ready for new machines.