As you want to transfer data too, I suggest you to use Setup Assistant or Migration Assistant. You can restore your data from Setup Assistant if you haven't set up the MacBook yet, and it's the most recommended method > http://pondini.org/OSX/SetupLion.html If not, use Migration Assistant > http://pondini.org/OSX/SetupLion.html
You say that you have an iMac G5, but then you say Intel. That doesn't exist, so we have to know if your old Mac has got a Intel or PowerPC processor. To know it, open > About this Mac, and tell us which processor it has. Depending on the result, you may have problems with some apps, because PowerPC applications aren't compatible with OS X Mountain Lion.
If you have an Intel-based Mac and you have Mac OS X Tiger, you have to transfer your files manually. In this case, I recommend you to reinstall Aperture from the DVD you purchased it
You'll need both the original and upgrade serial numbers to run Aperture on the new system. There is no way around this.
You can get the upgrade serial number from the old Mac, run Aperture and then do Aperture->About Aperture. The license number for the upgrade will be displayed.
If you can;t find the original license number see Pro Application Replacement Serial Numbers
good idea, but Aperture does not not transfer the licence codes when being migrated. It will check, if the system is the same.
However, everything I open Aperture on my MBP, it keeps asking me to enter the license code. FYI, I purchased the original Aperture via online download and subsequently bought the upgrade via local Apple reseller store. How do I overcome this?
did you originally buy Aperture 2 and then upgrade to Aperture 3?
You will have to enter both serial numbers, the original Aperture 2 serial number and the Aperture 3 serial number. And you will have to enter them signed in from an admin acoount. DO you still have both licence numbers?