Well that benchmark you linked was showing a stock 400mhz 7800gt. In addition, that was only 1 game, the difference in other games was way lower. Even so, that 15 fps difference you wouldnt even notice in BF2. Also that benchmark was done with old nivida 81.98 drivers. The newer drivers perform better. So those are a few factors to consider. A 470mhz CO SE is way faster than a 400mhz stock card.
Both are great cards. ATI and nvidia both make great cards. Id still recommend getting the 7800GT CO SE as others stated. Its cheaper than the CO and is identical. Dont ask me why. Supposedly the 7800gt CO SE is 460mhz, where as the CO is 470mhz. However I can tell you all CO SE cards ship with the CO bios, so they run at 470mhz as well. The point of that? I have no clue.... To answer OP's question, yes an EVGA 7800GT CO SE(470mhz) is faster than a BFG 7800GT OC(425mhz).
I have the evga 7800gt CO SE myself. Mine was $240AR @ Monarch about 1-2 months ago. Definitely best bang 4 buck if you ask me.
Thats what I would suggest getting. I can tell you that a stock "normal" 400mhz 7800gt is about 10fps at the very most slower than a GTX. Well, the 7800GT CO SE, is 470mhz, which makes it easily faster, or at least on par with a gtx. So thats something to consider.
Another thing you might think about is buying one used off forums. I just recently bought a used BFG 7800gt off forums for $200 shipped for a friend. So $200 for a 7800gt is a pretty nice bang-4-buck. Just something to think about.