What is with the old machine? Can you launch Aperture there at all? For example on a new empty Aperture library? Then use the the command "Aperture > About Aperture" from the main menu bar to show the "About" panel and take a note of the serial number shown there. Write it down.
I still don't get any updates available when I choose Software Update from the Apple.
What is the MacOS X version on you old computer? Is Aperture installed in the Applications folder?
When I put Aperture 3.0.3 on the new machine I could not open my Aperture library. Now I can't update the library. I don't have the original serial number for the application and can't open it
You need to update Aperture on the new machine, before you try to launch it on your new machine.
Have you installed Aperture by running the trial or by copying the Application? Run again the Aperture Trial installer on the new machine.
- Download the Aperture Trial version from here: Aperture 3.1 Trial
- Now run the Aperture trial installer on your new mac and upgrade immediately (using Software Update from the menu). Then launch Aperture and unlock it with the serial number you retrieved from your old mac from the "Aperture" about-panel.
Chris, under certain conditions Apple will give you a replacement serial number, since Aperture is a Pro application. Contact Apple for a replacement as described here:
Pro Application Replacement Serial Numbers: http://support.apple.com/kb/HT1861