Dimension 4500 Video Card ?

[Osyris]

I have a Dimension 4500 and I am looking to replace the video card on it. I have a 250W power supply and I am looking to get a card that will give me the best bang for my buck. At this point, I really dont want to replace the power supply.

Any suggestions as to what card I should go with? I browsed the earlier posts, but the answers were a little hazy.

thanks!