First, I'm not a huge fan of the Antec 1200. I think it's overpriced. Instead, I'd check out the HAF 922 (easily the best case on the market). Other good, cheaper options include the Antec 300 Illusion, Antec 900 (or 902), Coolermaster 690, Rosewill Challenger or anything from Lian Li. I'm not saying the 1200 is a bad case, just you're likely paying too much for it.
On to my other problems with the build.
PSU: That's a poor quality unit. I'd definitely get a 650-750W unit from Corsair, Antec, Silverstone, SeaSonic or XFX instead.
GPU: You list your uses as CAD work, buy you've got an ATI card. nVidia's cards are drastically better than ATI's for that kind of work. I'd get either a GTX 460 1 GB (cheaper, but less powerful) or the GTX 470 (more expensive, but more powerful). I'll caution you that the 470 runs very hot and uses a lot of power, so if you're planning on SLI later, you'll want an 850W PSU.
Mobo: Not a great choice either. I'd grab the Gigabyte GA-X58A-UD3R instead. It's in a combo with the 950 to save a little bit of money.
HDD: Horrible choice. The 7200.11 is known to be problematic. In addition, it's an older, slower model. I'd switch that for the Samsung Spinpoint F3 1 TB. It's smaller, but more reliable and a lot faster.
RAM: Basically you can get any 3x2 GB kit. I'd recommend 1600 mhz CAS Latency 7. The only brand to avoid is OCZ, as their DDR3 sticks have compatibility issues with Intel boards.
You may want to change your videocard to a 460GTX or 470GTX (similar price range) to utilize CUDA technology which helps performance rendering in Photoshop, AutoCAD and other 3D programs.
If you want to not upgrade your computer for a few years, I can recommend a step higher to the 570GTX.
The I7-950 with the X58 Saber works well (I work in retail computer store and have sold many of this combo).
As for memory on the 1366, you can go with a 6GB or 12GB depending on how many applications you will leave on your taskbar. I can recommend the Patriot series or Kingston brands for memory (OCZ does not follow the JEDEC standards, so there's a higher possibility it may not be compatible) or you can follow the QVL.
Note: Since you are purchasing from tigerdirect.CA, you should be around where I work actually (Infonec Computers). If you want, you can come visit me and we can discuss more face-to-face.
@matyar, I saw your online store and I'm glad there's another store out there that sells stuff cheaper than tiger. I would love to come by and chat but I still have exams 'til the 23rd. To add more, I'd be more likely busy over the holidays. I may do business with you if the price quote from your store is actually cheaper than canadacomputers. Oh one more thing, will you guys have any sale any time soon? Boxing day perhaps?
Once again, thanks for the input. It really means a lot. I'm still open for suggestions. (Cheaper alternatives perhaps. )