After having a peek at Apple's new guided Quicktime tour of Mac OS X 10.5 Leopard, we're convinced that Time Machine alone is worth the upgrade price. Time Machine is Apple's new backup and recovery software, but it's actually quite a bit more than that. The program makes use of external storage devices (like, say, a USB 2.0 hard disk) to create backups of your entire file system.

You can later browse the Time Machine copy of any folder by navigating a useful timeline. In this way, you can regress through previous versions of the folder. This is a fantastic way to keep from losing files or just do a simple form of revision control. If you need more time range in your Time Machine, it's only a matter of slapping on a new external drive.

Now, we realize this kind of backup and recovery has been done before, but when you see how sell it integrates with Finder and Spotlight, we think you'll be just as anxious as we are to get your hands on the new OS X.