I'm assuming that your source media isn't contained in one folder, but scattered throughout the iMac. In which case, open your project in FCP, Click "File", then select "Media Manager". Since your project isn't complete, don't select "delete unused media"...instead, just use the Media Manager to COPY your media to your iBook...which brings me to another concern...
Since your project was created in FCP5 on the iMac, and since FCP 5 isn't compatible with 10.3.9 (as far as I know), you need to keep in mind that project files are not backwards compatible...meaning, a project created in FCP 5.1, cannot be opened in FCP 5.0.4 or below.
Just some food for thought.