Well I suppose it depends on how thorough you were in deleting P.S. stuff if you did it manually without using the preferred uninstaller application. The Uninstaller app should be located at Applications-->Utilities-->Adobe Installers-->Add or Remove Adobe Photoshop CS3
In addition you may need to use the Adobe CleanUp script after that. It was originally posted by Adobe to help with fully removing the final scraps of code that were left over after running the uninstaller in the Photoshop CS3 beta versions and such, but a couple of people I have recommended it to have used it successfully on release versions of PS CS3, again only after running the unistaller app in your Utilities folder. You can get the CleanUp script at:
BTW- If it was a release version, hopefully you deactivated the installation before you started deleting things- if not, then reactivating with Adobe (when it might be reinstalled sometime down the road) will require a phone call to them to reset the status of your activation code.