Do you have or are you planning to run any programs that absolutely require a Quadro card? If not, skip that Quadro 2000 altogether: It by itself costs about $400, yet is slower (clock-speed-wise) than the $110 GeForce GTS 450 that the Quadro 2000 is based on.
The only applications I forsee using are the Adobe CS5 family as indicated... So, no, no specific need for the Quadro indicated. I want to make sure that the card has the capability of "unlocking" the advanced rotation/zoom capabilities in CS5. My present card requires that I still use the "stepped" rotation/zoom.
I looked at a comparison between the GTX 560 Ti ($250) and the GTS 450 ($125) and see that the 560 performance far exceeds that of the 450. At i/2 the price of a 2000 would this be a good card?
Your thoughts on the rest of the build? I'm getting too old for all this... I just want to turn it on and have it work...fast!
Go for a big tower, not a mid-sized one. Better airflow, cable management and cooling, easier to install and more expansion room.
Why a separate NIC card, when there is an on-board NIC?
On-board raid is OK for non-parity raids. So either striped or mirrored, like you intend. The 560 is a good card and BFTB wise (bang-for-the-buck) it is one of the best choices at this moment.
Look at a good third party cooler from companies like Noctua, Prolimatech or Cooler Master, especially if you get into overclocking and forget about water cooling, unless you intend to go into extreme overclocking or are looking at shaving off 1 db of sound.
What PSU are you looking at? I suggest at least 850W, but better 1000W Gold rated PSU from Cooler Master.