Gaming Build in July/August, Need Your Expertise

I've been looking into building a gaming computer for a couple of months now. I don't really want to Overclock, this is my first build and I don't want to screw it up. Thank you to everyone for looking at this and helping me out, I really appreciate it.

so far this is my config:
---------------------------

Monitor - Viewsonic VX2025WM 20.1 widescreen LCD - $330.00
http://www.newegg.com/product/prod [...] 6824116381

Case/PSU - NZXT Lexa w/ PSU - $150.00
http://www.newegg.com/Product/Prod [...] 6811146017

CPU - Intel Conroe E6600 - $310.00

Motherboard - Any advice would be awesome (preferrably $150-200ish)

GPU - Radeon x1900xt - $375.00 after rebate
http://www.newegg.com/Product/Prod [...] 6814127206

RAM - OCZ Gold Series 2GB - $150.00 after rebate
http://www.newegg.com/product/prod [...] 6820227047

Hard Drive - Western Digital Caviar 250GB 7200 RPM 16MB Cache SATA 3.0Gb/s - $80.00 after rebate

DVD-Rom - anything thats a good brand? - $20.00

DVD-RW - anything thats a good brand? - $35.00

if necessary...

PSU - Antec TRUEPOWERII TPII-550 ATX12V 550W - $70.00 after rebate
http://www.newegg.com/Product/Prod [...] 6817103931

TOTAL SYSTEM - Roughly $1600.00ish depending on what I end up with

Now for the questions????

1. As for the GPU. Should I stick with the x1900xt (do the brands make a difference MSI, SAPPHIRE, ect?) Or drop it to a x1800xt? Or I was thinking about getting cheap one and waiting for a DX10 card. (not sure if I should go ATI or NVIDIA, from what I've read ATI seems better.)

2. Also on the GPU topic. My friend has a 2nd NVIDIA 6800gt (<- i think) he got really cheap that he isn't using for SLI right now. It's possible I could borrow that then get get a dx10 card when they come out. If i get a motherboard that is an ATI chipset, could I use a NVIDIA card?

3. Is this powersupply that comes with the case crap? I hope it's not, but if it is I was thinking about the Antec listed above.

4. What motherboard should I get? Specifics would be great, like brand and model number. I might go dual GPU someday so I want sli/crossfire. Around $150-200...Preferrably $150ish lol

5. Any other suggestions for the RAM, anything thats DDR2 and around $150.00. Not sure if I should go OCZ, Corsair XMS, or Crucial.

6. Do I need a heatsink fan like the zalman? I don't know anything about that at all. Any recommendations and advice would be great.

7. MOST IMPORTANT QUESTION!!!
Will this get the job done? I don't want to have to upgrade for 2-3 years. I want to be able to play the new games (Crysis especially) on High settings.