Scott_D_Bowen :
You'd want to go Xeon's based on your desire to have a workstation (vs a consumer PC) and the kind of software you're likely to be running.
Look at ECC Registered x4 (not x8) RAM too, and plan to keep the thing around 'til it has 128GB of RAM if you can.
Many individuals, and even companies use regular i7's (even i5's) for "workstations". Don't just parrot Intel marketing literature. It's a little more complicated than just "you need a Xeon and a Quadro for a workstation, end of story".
Rather than just repeating marketing hype, why don't you link to tests, comparisons, benchmarks or other examples that illustrate the difference between Xeons and "consumer" grade processors, in those type of programs that the OP listed, so everyone has a chance to be more informed?
Xeons are allegedly more "reliable" and "durable" under the constant, heavy usage that you would have in a work situation. At least that is what Intel "says". OK then, where is the data to support this? Forgive me if I do not just take Intel's word for it, I need to see some proof.
What does ECC RAM do for CAD and Graphic Design software? How much does that really increase performance and reliability with those programs? Show us.
As others stated, you would need to jump up to a Xeon if you felt you could benefit with more than 6 cores (currently the limit for non-Xeon i7's) or you want to have a dual-CPU setup. If you have the budget and you are doing lots of CPU-based rendering (3DS Max Mental Ray), then, yes - you most likely want Xeons and 8-16 cores. However, bear in mind that for the programs that utilize GPU-acceleration (iray, Vray-RT, some of your Adobe software) you really just need something with a lot of CUDA cores, and the right driver support. Supposedly, even the GTX-5xx Geforces perform well in this regard, look around for some benchmarks and performance comparisons. The Kepler 6xx Geforces are reportedly hamstrung from performing GPGPU up there with the pro cards, though; I guess Nvidia wasn't too appreciative of the fact that folks could get pretty good GPU acceleration off of their "gaming" cards.
If you are saying money is no concern, than by all means, go all out and get dual E5-2687W Xeons (each one will set you back ~$1,800-$1,900), for the cores and the high clocks (the less expensive E5 Xeons are slower) and a Quadro along with a Tesla, for the ultimate in CAD performance and GPU acceleration.