The CS4 installer will allow you to select by checkbox each application so you can just install After Effect.
before you do that though make sure you check your program files directly for the AE older.
Thank you Rick. When I look under the program Files Adobe > Adobe After Effects CS4 > the only folders and files are Mocha (Folder) Support Files (Folder) and the Mocha for Afetr Effects Shortcut.
So, um, I guess I'll do the first trick you suggested - just check the AE box and install just that. Do you know if I start with the first of the 4 discs?
The check-box re-install did the trick. Thanks!