I'm going to be running applications such as solidworks 2013 and autocad.
My question is:
Is it better to have a core i7 with no graphics card or a lower processor such as core i3 with a decent graphics card?
Maybe, BUT ... hard to see where the increase in cost justifies a small percentage bump in performance.
Where differences in CPU performance would be measured in small percentages (the FX Piledriver cores are quite proficient in multi-threaded applications), increases in performance via the workstation pro cards these days are measured in multiples of 2X to 3X or greater, meaning the the best return on your dollar is from your investment in the pro card.
Example: The difference in cost between an i7-3770 and the FX-8320 is $120. That cash in itself takes you over 60% of the way to a 2GB FirePro V5900 from a FirePro V4900.
The FirePro V5900 versus the V4900 doubles card memory, has more shaders, and improves geometry, while allowing you to really crank the AA for greater realism, with improved output and performance.