Still no luck.
I used 7-10_vista32_dd_ccc_wdm_enu_5325.exe, unpacking to the standard location. I ran the modtool 0.8.8.0, successfully with no log.
I used DriverCleaner and rebooted a few times first. Then I tried to install from the modded setup.exe.
Catalyst installed fine, but the display driver did not. The ATI log says:
"Driver Install: the specified driver package was not installed for matching devices"
Suggestions? And even if this works, will I get decent enough performance to watch a video without tearing?
Because this thread suggests there is nothing I can do:
ATI Mobility Radeon 7500 in Vista