What is the best sff(small form factor) video card i can put in my xps 200?

I have been endlessly searching for a way to improve the gaming performance of my dell xps 200, which came standard with an ati x600 se 128mb video card, which simply isn't enough for games like oblivion. My pc performance is great, i just need a better graphics card, and it needs to fit in the case(sff). I've looked at an x1300 sff, which is mediocre, and i was wondering if anyone knows of a half-size video card with good performance. oh and it also needs to run on a 300w power supply.|||SFF are NOT gaming machines. You're pretty lucky having a x600 in it. Not much better can be used except maybe a x700. You need a real computer that can support a full size video card in order to play games like oblivion. Just goto www.tomshardware.com for benchmarks.