Mac OS X 10.6 Snow Leopard upgrade works on Tiger 10.4 machines
This is somewhat controversial because it is against the Apple EULA, but apparently you can save $140 if you’re a Tiger 10.4 user and run the 10.6 Snow Leopard upgrade without a problem. To make things even more interesting, popular Mac writer Walt Mossberg actually recommends that you do this if you are a Tiger user. So it’s really up to the end users, either save money and upgrade directly, or go the other route and you’ll be out $140.
Mac OS X 10.6 Snow Leopard is a great upgrade and it’s one I would highly recommend installing on any compatible Mac. The fact that you can save a lot of money by upgrading directly from 10.4 is a huge bonus.
As with all software upgrades, be sure to backup your data before installing.