$200... alrighty then! I would suggest:
Radeon 9800Pro - Sapphire - $142
GeForce 6600GT - XFX - $154 (mail-in rebate), eVGA - $163 (mail-in rebate)
GeForce 6800 - XFX - $204 (mail-in rebate), eVGA - $199 (mail-in rebate)
I'm also assuming your looking for AGP and not PCIe, and this is why you don't see any X700s on there (on par with the 6600 GT). If not, correct me, and I'll find some other cards for ya. On these cards, it all depends on how much you want to spend. I would, of course recommend the 6800. However, if you don't want to spend that much, the 6600GT would be my next choice. Personally, I've got a 6800GT and it is awesome. Whatever you decide though, you'll probably be happy with any of these cards. They will all perform much better than what you've got now.
EDIT: Some other stuff I thought about. All of the cards are linked are 128 Mb. If you can find the same cards with 256, and it's still in your price range, that is another option. Second, always shop around before buying. Lots of online stores have specials and such going on. My personal favorites are NewEgg and ZipZoomFly (very fast (and free: ) shipping!). However, it doesn't seem your from the USA, so look for a reputable company in your area. Have fun with your research!