So you're checking off "Windows projector (exe)" and "Macintosh Projector" in the publish settings and generating whatever.exe and whatever.app from a PC and then moving the whatever.app folder to your powerbook?

Depending on the size of your SWF, the .app folder should be around 11.5 MB on the PC before you move it. It contains a lot of files, including the standalone Flash player that you'll need on the Mac side for everything to work.

If you can't copy the .app folder directly to your Mac via a network share then ZIP the .app folder before you upload to an FTP site (or however you're getting it to the Mac) and then unzip it when you get it to the Mac.