The list looks great to me with one exception: The video Card. If this is going to be a CAD workstation, depending on what CAD package you choose, the graphics solution can make or break the usability of the workstation. If you can swing it I would recommend spending the extra hundred or so bucks to move up to at least a Quadro FX1300, I think you would be happiper with the performance. Having used workstations with cards at both ends of the spectrum (entry level and over the top) it can be extremely frustrating if your graphics card gets in the way of your CAD work.
I did end up changing my motherboard to an Asus A8n sli premium. I didn't need the SLI but I like the passive cooling and it just seems to be a generally reliable board with great features at a pretty reasonable price. Plus, if I really get serious about the CAD sometime, I could get quadro sli cards (which is another reason why I went entry level to begin with -- I didn't want to go mid-range only to upgrade to sli down the line).
I also switched to 3 Gb/s drives because the new board allowed me to. All Seagate Barracudas.
Lastly, I upgraded to a slightly better power supply: XCLIO XClio 450BL ATX 450W. I like the design with the big fan on the bottom (not aesthetically but thermally).