In my case I bought a used half space Radion X600 series DVI card with a Y DVI splitter from Ebay for my Optiplex that is running Vista. Vista ends up installing ATI Radion X300/x550/x1050 driver.
I also installed the ATI Catalyst Control Center.
Problem will be that extended monitor config will work but not after reboot or after computer is logged off until I FIX...
Go into device manager, uninstall the two monitor entries and also check box to delete the driver which will appear after uninstalling the first monitor entry. Once both monitors are uninstalled the monitor entry in device manager is gone.
Shut down the computer, restart...computer should come up with both monitors working but cloned by default. Configure the displays for extended desktop. Once it is working as desired, go into profile manager, delete any existing profile and create a new profile, name it...save it...activate and close. Reboot the box to confirm that the configuration sticks. Problem solved.