A Faster Optimized Upgrade that will be a least as fast or faster then windows on the internet!
A Upgraded Finder incorperating Coverflow makes it less stressful on your eyes.
SPACES makes the most of your desktop. Have programs launch at Startup and populate different Spaces with Programs and documents that are used on a regular basis. Saves Time!
Dictionary now has Wikapedia buit in!
Mail has Stationary to make your E-mail look professional!
Safari is faster then ever and has TAB's!
Time Machine is a simplified version of a backup system that works.
Leopard has detailed thumbnails and if you highlight the icon and hit the spacebar a preview of that file will open for most applications.
The real beauty of Leopard is that it is more of a complete package. Doing upgrades from a previous system will hold your settings unlike tiger where you had to go back and reconfig things like mail and keychains.
Parental controls are more complete when you setup an account.
Well you get the picture Apple has taken their OS 10.4 and improved it to a no bull and complete system with Steve Jobs guiding its way.
There are over 300 changes to 10.5 over 10.4 but these are some of the obvious ones.