"Out of all the reviews I've seen, I think everyone gets about 3mhz more out of it, so I wouldn't really expect too much."
I can get 10 outta mine without any mods; prolly more if I had a little cooling. There is also a voltage tweak mod at XBit that enables you to get more (some say up to 200Mhz) - I'm not willing to take a soldering iron to mine though, so I ain't trying it!