Snow Leopard is no longer available for purchase online

[Bandit Bill]

Apple has discontinued selling Snow Leopard through their online stores. You can still purchase Snow Leopard but you must phone Apple to place an order.

If you plan on upgrading beyond Tiger 10.4 or Leopard 10.5, you'd better call Apple and order Snow Leopard 10.6 while you still have a chance or else you will be stuck with 10.4 or 10.5 forever.

There are ways of performing a clean Lion/Mountain Lion install, but that's another issue all together and requires more know how and work than the average user wants to deal with.