Photo Editing Rig Hardware - Suggestions & Advice Please

Hello All at MG! I'm building myself a rig that I will be using for professional photo editing (mostly photo processing...I'm a photographer). However this will also be my main use computer for pretty much everything else. I want it to have the capability of playing demanding games, and also be able to run demanding software. The software I will use or may use on it is listed below:

Photoshop, Digital Photo Prof., ULead, UniGraphix, Fluent, AutoCAD, MatLAB and games: Flight Sim., BF2, CSS, etc. you get the picture.

Basically the biggest challenge here is reducing time it takes to compile something, such as an image or a CAD drawing. HOWEVER, I am not planning on Overclocking this rig for safety reasons. I need a stable, reasonably cool system to ensure the safety of my work. With that being said, lets hit it.

I. CPU - Quad core or Dual core? I assume quad core will give me more capability to multitask (edit images while others are processing). I am eyeing the Q9550, as I'm impressed by the 12MB cache and 1333Mhz fsb. However how much will I lose with a Phenom X4? Is AMD good enough for what I need? I assume dual-core will be outperformed by either. So Q9550 vs Phenom 9950

II. RAM - DDR2 or DDR3? Will I gain performance where I need it, or will my experience be unaffected? DDR2 will probably give me more memory from the start due to price. However with faster FSB (intel) will the whole system run smoother? I'm probably looking at 4GB DDR2 - 1066 vs 2GB DDR3 1333 or 1600 to start. Will the memory better affect the performance of the Q9550?

III. GPU - Nvidia or ATI? Will Nvidia run smoother with Intel and ATI with AMD or no difference? My main concern is memory: GDDR5 ATI vs GDDR3 Nvidia: Will I see a gain in what I do? Will Crossfire or SLI give me any performance boost or will I be blowing $$$?

IV. MB - Abit, Asus, Biostar... will repost my options when I settle on the above.

V. HD - 2x7200RPM 500GB 32MB Mirrored. WD vs Seagate? I like the 5yr warranty for same price. I assume the larger cache will improve performance. I will probably add another hd set, so that I can use one for compiling, while accessing software and other stuff on the other (install photoshop on same drive as photos per say). I also dont feel comfortable exceeding 7200rpm as safetly and longevity is a big concern---any thoughts?

That is all for now. All the rest is obviously not a problem for me. Although if anyone can recommend me an excellent S-PVA panel for under 400 that would be great. Right now I have Samsung 225BW TN obviously not photo editing material.

BUDGET (tower) : ~$1000
sample - Q9550 - 320
- MB - 250
- OCZ 8GB DDR2 1066 - 200
- XFX8800 GT 512MB - 180 << pos. future SLI upgrade
- 2HD - 150
- CM Centurion 5 +Rosewill 600W - 110
total ~~ 1210

Thanks to all for their input!