I'm running a 6950 and it hashes at 319 mh/s. I use guiminer with the -v -w 256 option in it. If you're getting 324 then I'd say your settings are about right.
Goes to show...should have read the newbies section when I joined...Have 20 hours and not a single post...I like lurking, and now when I need to post for a group buy of chips I can't post in the hardware forum...dang