You're in the wrong forum.
If you wipe off both CS3 and CS2 without the original CS2 disks, you will not be able to install CS3. I'm pretty sure that's the way it works with upgrades.
You need a prior full version's serial number to be able to install an upgrade version with most Adobe applications.
Does anyone know of a fix that does not include removing the entire package(s) and reinstalling?