although nVidia is the card of choice by SOE, I had great success running on my 9200 series ATI card, just make sure you get the latest drivers from ATI, that was causing me lots of problems earlier on.
when Vanguard came out, I switched to an nVidia card, but the ATI serves me still running my browser so I can look up raid info while in-game without taking up valuable game screen real estate. :)