I second increasing the budget a little bit. Either that, or at least get a good enough cooling style to be able to overclock the hardware to last a little while longer. Personally, I would take the above Gigabyte board and stick a GTX260 on there or an ATi Radeon 4850 if you really want to last for years. But yet again, considering back over a year ago when I was running the GeForce 8800GT with no SLi in my current rig (when I first built the thing, dang!), that card would run through games like Crysis, but it did run them quite well. It really only choked over Crysis when I turned up the Antialiasing any more than 8x MSAA on that card.
But other than that, if you want an 8800GT on Steroids, go with a 9800GT. I would at least shoot for a GTX260 if you can cough up the extra money though as it'll last you a bit longer, unless of course you're planning to build a new machine soon, but the 9600GT should be fine. As always, I suggest going double slot cards. They run cooler
