Sorry to ressurect such an old thread, but I just now read this and I wanted to clarify the point I was trying to make. I guess bottleneck was the wrong word to use. What I meant was overall system performance.. You would get more performance out of your system by buying a quad core with your 8800 rather than sticking with what you have now and getting an 8900gtx.
[CPU: e6600 @ 3300 MHz] // [MB: ASUS P5N-E SLi] // [RAM: Patriot 'eased latency' PC2-6400 @ DDR800 5-4-4-12-2T] // [GPU: 8800GTX @ 650/1000/1600 (volt modded)] // [HDD: 2x Cavier 500GiB stripe] // [Chassis: Thermaltake Armor VA8000 (black)] // [PSU: Aspire(Apevia) 680w] // [OS: Windows 7 Ultimate x64][Cooling: water cooled GPU and CPU]
^ (9/7/2010): Ha, I remember when that was the stuff. My water cooling has since leaked and fried my mobo. So now I'm rocking an MSI laptop with an i5 430m :)