Among the many tools out there for cloning drives and performing full-system backups, one came to my attention for being both free (and open source) and powerful: Clonezilla, a product of the Free Software Labs of the National Center for High-Performance Computing in Taiwan.
Clonezilla's power, however, is matched by complexity. You can get a lot out of it, but at the cost of paying close attention to what you're doing. Here's a guide to getting just what you need from Clonezilla -- without wreaking havoc on your system or being swallowed by the monster.
Clonezilla performs two basic kinds of disk-copying operations: disk-to-disk and disk-to-file. Disk-to-disk is exactly what it sounds like -- a way to directly copy the contents of one disk or partition to another. Disk-to-file copying allows a disk or partition to be saved to a series of files, which are kept together in a directory located on either a network-attached disk or a locally mounted one (for example, a USB-connected hard drive).