When I tried to open the old aperture library on the new machine, it said I need to upgrade the application itself first, and that the new aperture can't simply import a library from the previous version.
How have you been trying to open the old library? It should work to double-click the Aperture library on your new machine to open it in Aperture 3.5 and let Aperture upgrade it.
The error message suggests, that you tried to import the library instead of opening the library.
Is you Aperture version on your MBP older than Aperture 3.3? In that case I'd recommend to run a "repair Library" with your current Aperture version in the MBP before copying the Aperture library to the new machine. A library upgrade is risky, if the library has any glitches.
To run the "Repair" launch Aperture with the key-combination ⌥⌘ firmly held down, until you are seeing the First Aid panel.