I went to the computer store the other day looking for a video card upgrade from my existing 800XL and I purchased a X1650 Pro 512 and installed it and ran 3D Mark 2005 and noticed a score of only 4,550, a far cry from my existing 800XL which got a 5,200 .... The only real advantage I did notice was the fact that the X1650 supported S.M (Shader Pixel) 3.0 ....
How do I measure which card would be considered an upgrade to my existing X800XL?
Keep in mind that card choice depends on much more than just benchmark numbers. Movies will look better on a X1600, and of course SM3 games. A 7600GT is a great choice too. It sounds like you are still on AGP (as I am) so it depends on the specs of your entire system if you want to invest more in it, and how much, and how long you'll use it for current games.
You have to use the "grain of salt" test on these forums. It's all very subjective. Some people want the best visual quality and buy a high end card. Some will buy that same card and turn the quality down to crap mode so they get max FPS. You can't always tell where somebody is coming from when you read their advise.
In my case, I bought a X1600 last May knowing my AGP system was end of life for my uses. In a couple months it goes to my 8 yr old for that level of gaming, homework, and watching movies in her bedroom. Perfect for that use for several more years with minimal investment.