Geforce 7600 GT
Codename: G73, 90-nanometer technology
12 Pixel shaders, Five Vertex shaders, 12 Texture units, Eight Raster Operator Units
128 bit memory bus
560 MHz core, 700 MHz DDR (1400 MHz Effective) Memory
The 7600 GT is an amazing card in this price range, sporting new SM 3.0 technology and very high clock speeds to deliver excellent performance. Its weakest feature is its 128-bit memory bus, but its high memory speeds offset that disadvantage and make it competitive with 256-bit cards like the X850 XT.
I will mention that ATI's new competitor for the 7600 GT may arrive in November: the X1650 XT. With 24 pixel shaders, it may have the power to compete with or even beat the 7600 GT in this price range, but it is as yet unreleased. Still, if you're purchasing in November, check if the X1650 XT is available yet and how its benchmarks compare to those of the 7600 GT.
Best PCI-E Card For ~$180
Radeon X1950 PRO
Codename: RV570, 90-nanometer technology
36 Pixel shaders, Eight Vertex shaders, 12 Texture units, 12 Raster Operator Units
256 bit external memory bus (512-bit internal ring bus)
575 MHz core, 690 MHz DDR (1280 MHz effective) Memory
The X1950 PRO is similar to the X1900 GT, the main difference being that it is not based on the X1900 XT, but a whole new and less power-hungry core.
The card's main competition is the 7900 GS, which it soundly beats in almost every benchmark.
I have already seen brand-new X1950 PROs for as little as $165 on Newegg. At that price this card is an absolutely incredible deal.
Best PCI-E Card For ~$250: None
In this price range, the best buys used to be the Geforce 7900 GTO and Radeon X1900 XT 256mb.
Unfortunately, I can't find them for that price anymore. What we can find in this price range is the 7950 GT, which is a good card, but it is more expensive than the X1950 PRO and only offers similar performance. It is thus hard to recommend.
Supposedly, ATI will release the X1950 XT this month, which should be a recommended buy once it becomes available - assuming it can be bought in this price segment. Until then, keep your eyes out for X1900 XTs and 7900 GTOs, in case they resurface in the $250 range.