My current set-up:

Dell Precision T3400 Workstation

Pentium E6550 Core 2 Duo (2.33 GHz)

8 GB RAM (DDR2, 400MHz)

Nvidia Quadro FX 1700

500 GB 7200 rpm HDD

Windows XP x64 SP2

22" Widescreen Dell Monitor

Solidworks 2011 SP2

I am looking to update to SW2011 SP5 as soon as its available and am considering a hardware upgrade at the same time.  I did a quick look on Dell.com and it looks like a direct replacement for machine would run right around \$1200, not accounting for additional memory, and I would probably just transplant my graphics card.  Extra memory would add a few hundred to the cost, probably around \$1500 total for a new workstation with my same video card.

Or I could upgrade my current machine.  I did a quick check and I can get a 2.5 GHz quad-core for \$210 and upgrade to Win7 for \$140.  Total cost of \$360 after shipping.  I haven't checked on compatibility, but maybe I could add a 128GB SSD for \$250. 

My primary use is basic modeling, but I am doing more PhotoView rendering (still and animations) than I used to and occasional simulations.

What do you guys think?  I will try to post a performance score sometime soon.