My Leopard installation was working pretty well until recently, when its EFI partition somehow became terminally corrupted.
I've now installed Snow Leopard as per this guide, and I can't believe how much better it is: faster to launch applications, fewer irritating glitches like the need to reconnect to the airport network after sleep, and a generally much more authentic OSX experience.
A very streamlined installation process, too.
Many thanks to the OP.