I'm an Nvida person myself, but I'll try to help.
Download the latest drivers.
Zero display service error is just that. Once the ati drivers are uninstalled, it leaves windows device manager without any "known" display devices thus the error as they are now "unknown devices".
fix 1) uninstall drivers, reboot, go into device manager, select display adapter ( unknown device) and manually give them default windows vga drivers then reboot and install ati drivers= no zero display error message.
fix 2) install drivers, get the zero display fluff, reboot, go into device manager and even though it shows they are installed, install them again manually. You should be fine now once you have installed them over manually. install your catalyst control panel software and use as normal.
Make sure you have installshield service, application management, .net runtime and dcom server process launcher services started. These are needed for safe installation. Dcom for installshield to work properly