This is a Toast image file for the Leopard Installation Disc. It works best with Toast: Open Toast, Select Copy, Select "Image File", Select the image file--->osx-leopard105.toast, Insert a DVD-DL, Burn the disc in the following name: Mac OS X Install DVD. Once it is done, ENJOY LEOPARD! NOTE: I have tried this. It installs very well, and has installed on five different machines: Macbook (4), and iMac Aluminum 20". The install may "Freeze" the first time, but second time is a charm :) Cheers Boys!