I recently needed to reinstall Windows XP, but I didn't perform a clean install with formatting the partition, but I installed on the partition without formatting, and it only deleted the windows files. Now I am trying to install Adobe Creative Suite 4: Master Collection, but I am unable to install AE with it because it shows it is still installed. I check the Add or Remove Programs, and also looked for the folder on Program Files, but I didn't find anything.
You just run some program from creative suite and deactivate to not lose your license.
You can use the CS Cleaner tool, which will clean up the installations and allow you to install again.