After zero'ing my HD and starting from scratch I've just gotten my legit copy of CS3 running with no problems. Me and a friend also wiped his HD, re-installed Leopard, re-installed his non-legit copy of CS3 and that is also running fine with no problems, even though it had to be unlocked on a 10.4 machine and copied back over.
The important thing is to delete all of the preference files in your user folder, and the Adobe folder in ~/Library/Application Support. The Adobe installer refused to run without the Adobe folder in HD/Library/Application Support/ removed.