definitely the GeForce 128MB 6600 GT is the best bang for that kind of buck nowadays, everyone agree on that. I upgraded recently from an FX 5700 ultra to the 6600 GT and I'm quite happy with it, noticeably better cards will only be for at least 2-3 times more money
PD just found this at
http://www.anandtech.com/guides/showdoc.aspx?i=2499&p=4
Mid-Range Graphics
Usually at this point, we speak of a NVIDIA 6600GT recommendation with remorse that ATI has nothing competitive to offer price/performance-wise in this $100-$200 segment. However, this time there's an interesting card showing up in channel from ATI marked "X800". The X800 uses the same ATI R430 graphics core as the High End X800XL, but only has 12 pixel pipelines instead of 16, which doesn't seem to hurt it very much while demolishing NVIDIA's 6600 GT and ATI's very own X700 Pro along the way - the two main cards that used to occupy this price segment.
Today, we found an MSI X800 PCIe for $145 [RTPE: MS-8997-01S] after rebate, though the usual price hovers around $175. X800 is without a doubt the best price/performance deal in graphics cards and will play all your games just fine. Unfortunately, this card is only recommended in PCIe, since the AGP version is $80 more expensive.
also... NVIDIA has dropped the price on the regular 6800 to an MSRP of $199. Most cards are still above MSRP for now (with many including mail-in rebates), but they should fall below $199 shortly. The choice between 6800 and 6600GT becomes rather interesting now, with prices and performance being very similar. The 256-bit memory interface of the 6800 usually wins out in our book, although the PCIe cards actually have slower RAM than the AGP models. AGP users will find the XFX 6800 especially interesting, as it is now $155 [RTPE: XFX 6800 AGP].