Hello - if you are planning on ordering OS X Leopard, I would ask that you consider pre-ordering it through our Amazon affiliate link. This is one of the few places that you can place a pre-order at this time.
Honestly I'm not getting a speed difference from it. And judging from the early returns on forums around the web, neither are most users. Not many features, crashes about as often as Firefox. I would say don't waste your time.