I have a machine with a similar vintage ATI card and when I installed the older CCC version, it hosed up the display. What worked, was doing the following:
1) Revert to the default MS video driver
2) Remove the full ATI CCC suite
3) Reinstall ATI, but this time, only the video driver, not the CCC stuff
4) Reboot

After that, the video worked fine. I don't have CCC, but with that old a card, you're not going to get advanced features anyway.