ATI Radeon 7500 &Open Source drivers for Debian “Etch”

Have a Lonovo R40 laptop that I have just installed Debian “Etch – testing” on and the maximum resolution that I can get is 1024×768 with a refresh rate of 60Hz using ATI Radeon 7500 Mobility video card. I had read once that you can get a open source driver that will allow you to get the maximum resolution of 1400×1025 on the R40 if you install the open source drivers. The bad part is I can not find documentation on how to perform this function with X.org. Has anyone ever used ATI open source drivers with the new X.org in Debian Linux and if so, what files did you have to tweak to make it work?