Backing up your data is a good first start, but what if you want to be able to easily restore the entire operating system just as you had it, with all the installed applications and exact same configurations? There are solutions available for both Mac and PC:

For Windows XP (or Vista, etc.), there is a free option and a paid option:

The free option for hard drive cloning for Windows is DriveImage XML.

The paid options are either Acronis True Image 11 or Symantc’s Ghost: I prefer the Acronissolution personally, and you can download a free trial here.

For Mac OS X, SuperDuper! is an excellent program. If you’re running Leopard (OS 10.5.x), you also have the option of using Time Machine (which is built into the operating system), but SuperDuper! is still worth the small investment. With SuperDuper! you can make a bootable image of a hard drive to restore the entire operating system.