i bought two of these: http://www.newegg.com/Product/Product.aspx?Item=N82E16814127555

i can easily get over 400 mh/s. with that said i have not spent enough time to see if i can get over 425 mh/s.
i just turned them up and do not feel like paying attention to them over the weekend so i went slightly conservative.
they are a reference card. i unlocked the shaders but stuck with 6950 firmware.
i use msi afterburner software with the voltage enabled hack.
without logging into my win7 x64 box.. i put fans at 80%. voltage at 1190. mem at 520. i attempted to use
that ati control crap software to do the 20% increase boost but somehow i am not sure if it worked right. i need
to read up on it. clock speed just a tad less then 1000. couple of fans around the setup i had laying around. no case.

guiminer (newest version)/poclbm   -v -w128 -f 2

my speed is in my sig.. so just minus out my lame 8800GT on my PC i am typing from you see what I am running at.
the 8800GT is good for about 20 mh/s. So i would say the two cards are comfortably above 800 mh/s.