ATiTool 0.27 Beta 1 Changes in version 0.27 beta 1:

* Added Vista support for ATI
* Added Vista support for NVIDIA
* Added Driver level OC option for improved compatibility
* Added X1950 Pro support via Driver level OC

This release does not work out of the box on Vista 64-bit. You need to disable driver signing.

http://www.techpowerup.com/wizzard/ATITool_0.27b1.exe