UNIX: Back up a hard drive with 'dd'

Create an image:
dd if=/dev/[device] fs=1k conv=sync,noerror | gzip -c > output_file

Restore an image:
gunzip -c output_file | dd of=/dev/[device] fs=1k conv=sync,noerror

Also works over a network:
dd if=/dev/[device] fs=1k conv=sync,noerror | ssh whomever@whereever "dd of=[device or file] fs=1k conv=sync,noerror"

NOTE: It's been a few weeks since doing the above. My syntax may be a tad rusty. ;)

When specifying the device, use the raw device (/dev/hda or /dev/sdb or whatever) without specifying partition numbers. However, partitions can be specified if you want to back them up on that basis. Dumping the entire disk also gets the MBR. You should be good-to-go.

Recommend you use a live linux distro or something similar. I use Knoppix.