In the latest Leopard update (10.5.2), they reversed a lot of changes that were made in the original Leopard release concerning the desktop user interface. For example, they brought back the opaque menu bar, and opaque menu pull downs. While you can choose whether the menu bar is translucent or opaque in the use preferences now, they took away the translucent menu pull downs without any option of keeping them the way they were in the previous release.

If you want to have the translucent menu pull downs back in Leopard, here's a post that describes what you need to do: http://forums.macrumors.com/showpost.php?p=5201771. It's a little bit complicated, but it does seem to work.