I have a MacBook Pro with Snow Leopard, which I'm planning to upgrade to Mountain Lion. After doing so, can I then use the Snow Leopard disks to upgrade an Intel-based Leopard desktop? Didn't know if laptop and desktop OS is interchangeable. And also if it matters if the laptop is Pro and desktop is not.
Nope' system disc's are machine specific.
Retail Snow Leopard Upgrade Disc's are no longer available at the Apple online Store, but if you call Apple Support they may still have some available at the original price.
Other options for obtaining a Retail Snow Leopard Upgrade Disc can be found at Amazon, E-Bay and on Craig's List, but the prices are going up everyday.