The drawback though is that the retail version of Leopard is very expensive, it seems to run $80-150 on eBay because it's in high demand among PPC users. You want the version with the black background, which is the retail version that will work on any Mac.
This is entirely true. I called the Apple Store via the 800 number and you have to request it. There still is plenty of NOS (new old stock) around. Revived my old PowerBook G4.
It's still rather expensive but a one time purchase that sure is better than pirating it. Especially considering it's a dual layer DVD.