As some have already said, SLI is not worth the cost right now. I have assembled a build based on your past "budget" build. Here it is:
Processor:
Intel Core 2 Duo E6600 - $316
Motherboard:
Asus P5N32-SLI Premium/WiFi-AP nForce 590 SLI - $215.99
Memory:
G.Skill 2x1GB DDR2-800 CL4 - $229.99
Video Card:
eVGA GeForce 8800GTS Superclocked - $409.99
Power Supply:
Hiper HPU-4K580-MS 580W - $89.99
Hard Drive:
Western Digital 320GB SATA 3.0Gb/s - $89.99
Case:
Rosewill ATX Mid Tower Dual 120mm Fans - $39.99
Total: $1391.94
With shipping, you're right on budget. The RAM I suggested is both cheaper and a bit faster than the Corsair RAM you proposed. Also, the Hiper PSU is a bit cheaper but is high quality (and SLI-ready).
As for video card, I decided to go for a single 8800GTS. Even if it's the 8800GTX's little brother, it still delivers amazing performance, faster than a X1950XTX. You can always buy a second one down the road if you insist on having SLI.