In Depth: Apple's Leopard leaps to new heights

As great as the Finder looks, a more important question is "How does it feel?" Leopard is more visually intense and uses more animations than Tiger, but all that visual scenery has no impact on performance, at least on more recent Intel-based hardware.

In fact, the new Finder feels much more responsive than it did in Tiger, which itself was a great improvement over Panther. It's easy to fly through the file system, whether the files are local or across the network, with nary a sign of the dreaded spinning beach ball cursor indicating that the computer is crunching data.

As an added bonus, the Finder now updates in real time. So when you dump a few gigs of data and empty the trash, the amount of free space on your hard drive changes to reflect the removal of those trashed files. It's about time.

Time Machine: Biggest undelete ever

Leave it to Apple to take something as mundane as backup software and turn it into a glitzy, almost-fun feature. And yet that's exactly what it's done with its new Time Machine application. Time Machine is probably the most-talked about addition, and with good reason. Not only does it offer the most radical user interface in the operating system, but it's also intuitive and effective in terms of form and function.

Quick show of hands: How many people back up their computers regularly? Right. Almost no one. Who wants to sit around figuring out what to back up, how to back it up and how to restore it? Most backup apps leave users flummoxed and at best simply capture a single snapshot of your files at a given time. The result: Most users plug away without a safety net, assuming their hard drives are fine until the day when suddenly they aren't.

Enter Time Machine, an easy-to-use application that allows you to back up some or all of your files and easily retrieve them should you need to do so. Plug in an external hard drive (or use a different partition on your internal hard drive), designate that as your backup disk, launch Time Machine, tell it which files to ignore, and let it do its thing. It keeps hourly backups of your files for the preceding 24 hours, daily backups for the past month and weekly backups until you run out of room. After that, it will begin to delete your oldest backups as newer ones are created -- although it will warn you first before doing so.

Setting up Time Machine is a snap. ()

Once you decide which files to back up, Time Machine starts a two-minute countdown before it gets to work. It runs in the background, doesn't slow the system down and -- after the first backup is done -- keeps only incremental backups, saving both time and space. It's almost set-it-and-forget-it simple. We'll have a more detailed look at Time Machine in the next few days.

There are a few caveats to keep in mind: It's best to do your backups to an external drive. If you use a partition on your hard drive as your backup disk, you're still in trouble should the disk fail. If you're not worried about that happening and all you want is quick retrieval of a file in the off chance you delete an important document or app, then go ahead, live on the edge. But for a real backup, your files will be safer on a second drive.

It's not the backing up of files that makes Time Machine the "wow" app of Leopard; it's the way you retrieve files later on. Trust us, you're going to be doing backups just so you can watch Time Machine do its thing.

After your files are backed up, click on the Time Machine icon in the Dock, and your desktop disappears. In its place is an almost hypnotic new desktop with a deep-space background image, complete with moving stars and a spiral galaxy image that looks like it was snapped by the Hubble telescope.

Time Machine's restore process elicits oohs and ahs. ()

In front of that "galaxy" is a series of Finder windows, each of which represents a discrete backup. The most recent one is in front; earlier backups recede behind it into the distance.

On the right side of the screen is a timeline, which you can use to scroll back in time to get to the file you need. Not sure which date to look for? You can use Apple's powerful Spotlight search function to find it. Since Time Machine is integrated with Spotlight and Apple's Migration Assistant, finding and restoring files, applications or whole systems is easy. There's more on Spotlight below.

If you use a laptop and don't want to lug around an external drive, Time Machine will track changes to all of your files since your last backup and record those changes the next time you plug in the backup drive. And while it seems logical that Time Machine would work over Wi-Fi using a hard drive connected to Apple's AirPort Extreme wireless base station, it doesn't, according to company officials. Bummer. That would make a fantastic app even more useful for road warriors looking for seamless backups over their own Wi-Fi network.