Looking to upgrade video card, don't know what to go with?

Currently I have a Radeon Xpress 200 series. I want to play World of Warcraft, and that card will not let me do it. Can anyone suggest a better, affordable upgrade for me so I can play WoW?|||i prefer the 9800 GT for best bang for your buck option, you can pick one up online for near 100 dollars, but make sure that your power supply is at least 500 watts as a minimum. Under powering a card will cause it to either not work, perform poorly, or damage it permanently, or all of the above.|||there is a $150 card that can run it good its called radeon ati 2600 xt its not the best but itll do the job