All looks well. Except you posted no motherboard :O I think.
I'd stick with the 920 because the 940 features the same 4.6G/T QPI. Basically just a higher clocked 920 for way more money. You can get that speed by OC'ing.
Make sure that the SeaGates you are getting are NOT the 7200.11 series. I would suggest 7200.12 only. The 11's have firmware issues. And the 12's have a better design. (less platters, heat, noise, etc.)
I'm not sure how large your monitor is or how much VRAM this program you use takes up. Make sure you are getting a GTX 260 Core 216. It has more stream processors. I think EVGA makes a version of it which offers 2Gb of onboard VRAM if you think it would be necessary. I've never seen or used the CAD program so I don't know what kind of resources it uses.
Should be an excellent build