How to fully delete Photoshop?

I made the mistake of trashing Photoshop CS3 and read afterwards that i should have removed the application. I've tried to reinstall Photoshop CS3 and the installer keeps stating that Photoshop is installed. Any idea how i can delete all elements related to the software?

open finder> search for "photoshop"> delete everything that comes up

yup, did that, deleted everything from my Library, preference and application support. I read that once i do this it should be fine and its what the uninstaller pretty much does. unfortunately i can't reinstall still. haven't tried the clean yet as it strongly suggests to backup everything first so i guess i should do that first...

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