Easiest to do, especially if you're familiar with flashing other things like your mobo bios. Just boot from a clean dos disk, run start.exe from the .zip file and choose a numbered option. Finish flashing, power down and up. Boot into WinOS and install drivers.
Its probably best to uninstall any current ATI driver you might have and uninstall PowerStrip if you use that before you do the above. I flashed my LE with a fresh install of WinXP and its now up to 275/275 default.