I need you to help me by telling me if this build is good or you can modify it to cost a bit less to somehow get my second SLI 9800 gtx in it:
 
   
 
1x Thermalright Ultra-120A CPU Heatsink  
1x Pioneer DVDRW x18 Black DVR-215DBK SATA  
2x OCZ 2GB Kit DDR2 800Mhz PC2-6400 Reaper HPC 4-4-4-15 OCZ2RPR8002GK  
1x Intel Core 2 Duo E8400 3GHz 1333FSB 6MB Box 45nm  
1x CoolerMaster Stacker 830 Black  
1x XFX nForce 780i  
1x XFX GeForce 9800 GTX 512MB DDR3  
1x Corsair HX Series 1000W PSU  
4x Zalman Case Fan ZM-F3BL BLUE LED 120mm  
1x Seagate Barracuda 500GB 3.5 7200Rpm SATA II 16MB
 
 
Thanks in advance

I would think that you could save a bunch by coming down on the PSU a bit.  My guess is the Corsair HX 1000W is going to run you $300.  You should be fine running 2 9800GTX cards in SLI on a less expensive PSU.  I'm planning a similar system around a PC Power and Cooling S75QB 750W.  Newegg has them for $150 (plus a MIR for $30).  They get 60 amps on the 12V rail, which is well over the 45 amp requirement I've seen thrown around in reviews.  That would save you almost $200, and give you a headstart on buying the second 9800GTX.
 
Either way, this looks like a nice setup to me.

If I was you, I'd scrap the whole SLI idea and get an X38 board. The 4870 is coming out very soon and will outperform anything currently on the market. Something tells me it's going to have a nice pricetag compared to the GX2 to go with it. The X38 board means you have better overclockability for that beastly E8400 and it also gives you the Crossfire option for the future.
 
Just my two cents.
 
 
Maroc.
 

 
 
I'm just being aware for the third one (in the future when I'll get low FPS)
What do you say?

 
 
1. I've never trusted ATI
2. Why do you say that the X38 boards have better overclockability ?

Yeah, if you're going with a 3rd card in the future, then I'm not sure that 750 will do it.  It may, but I've heard reviews suggest 1000W and 55 amps for 3.  I'm no PSU expert, so all I can tell you is what I've read.  Here is the review I'm referring to:
 
http://www.guru3d.com/article/bfg- [...] x-review/4

 
It's not a matter of trust, the ATI offering will be the best card, what is there not to trust?
 
And the X38 chipset just has something about it that makes it a great overclocker, the X48 is even better.