Well, you won't find me much help at all, as I'm very new to Linux...
You could try lowering the refresh to 75 Hz, or even 72 Hz if you can stand it
If your xf86config that you posted contains version info, it escaped me, but that really doesn't say much. You could find that info and see if it's the latest version of xfree86, and if it's not, update/grade. ATi doesn't offer official Linux drivers for the 7000.