Our assemblies top out around 5,000 parts, most are much smaller. I do occasional FEA, but it's not every day, or even every month.
Using 2010 premium and here is a workstation some local guys have quoted for me:
Cpu Intel E8500 3.16 Ghz LGA775 Core2 Duo 1333 Mhz
Memory 2.0GB DDR2 PC 5300 667 Mhz
Hard Dr 7200 RPM SATA
OS XP Pro
Video Quadro FX 580
It's quite affordable, but it kind of looks like minimum requirements to me. Have room to spend a little more if necissary.