Hi, Solie.
You can find the clean-up scripts here:
http://www.adobe.com/support/contact/cs3clean.html
I'm afraid yes, it will erase anything CS3, including the already released design suite applications. You can then install everything again. All of this should not be needed for the release version of AE (but removing the public preview with the uninstaller will still be necessary).
Adolfo Rozenfeld
Buenos Aires - Argentina
ar(AT)adolforozenfeld.com