by , 7:30 AM EDT, October 26th, 2007

The launch of Mac OS X 10.5, or Leopard, is only hours away, so it won't be long before G4 and Intel-based Macs all over the world are happily humming away with Apple's latest and greatest OS installed. When I offered some tips on preparing for a Leopard installation, I mentioned making an exact copy, or clone, of your hard drive. Today we'll take a look at what that means.

Clone
When you clone a hard drive, you are making an exact duplicate. Since this new duplicate is like the original in every way, you can use it just like the original. All of your files, the operating system, and applications will be exactly where you expect to find them. In most cases, your drive clone is bootable as well, so you can use it in place of the original if you need to.

Carbon Copy Cloner from Bombich Software is one application that can handle drive cloning without any problem. If CCC isn't your style, another nice option is SuperDuper! from shirt-pocket software.

Backup
In simple terms, backing up involves duplicating critical files so that if the originals are lost or damaged, the copies are available to take their place. If you aren't following a regular and reliable backup routine, you will lose important files. It's only a matter of time.

While a cloned hard drive does make a perfectly fine backup, it's usually more efficient to copy only the files that have changed since your last backup. That's where backup applications come in handy: They track your changed files and back them up on a regular basis so you don't have to remember to do it yourself.

Both Carbon Copy Cloner and SuperDuper! offer data backup options along with their cloning features. .Mac users can also take advantage of Apple's Backup application -- it has been serving me well for some time. After installing Leopard, Time Machine is an option, too.

My personal routine includes nightly backups to an external hard drive, weekly backups to my .Mac account, and twice-monthly backups to DVD. I don't like to lose data.

Making sure you have extra copies of your important files, either through backing up or cloning, needs to be a regular part of your computing routine. Even though things tend to go smoothly when installing new versions of Mac OS X, it's a really good idea to backup the files you can't afford to lose -- you never know when something unexpected will happen and things go horribly wrong.

The moral of this story: Backup your files or lose them.