1GB GT240 Good enough for Solid Works 2010, or should I go with FX 580

I am about to build a computer that I will mainly use for Solid works 2010:

Specs on build are:
Asus P5N-D
Q6600
8 GB DDR2 800
Win 7 64 bit Pro

I am torn on whether to use a GT 240 (95$) or FX 580 (190$)

I am not going to be doing extreme modeling, and I plan on building an i7 powerhouse in a few years (or whatever best of best is then) and really just need something that will help with rendering times.

I know the FX 580 would be recommended, but is it worth the extra 100$ atm?

Thanks!