Difficult Upgrade to 10.5

[Janit]

Your installer needs to be run from a bootable drive. You can make a bootable installer on an external drive or on a flash drive by using the "restore" function in disk utility.

Here is a guide for making a usb flash drive installer here:

http://www.maciverse.com/install-os-x-sn...drive.html

This guide is for Snow Leopard but the same process works for Leopard.