http://www.clonezilla.org/
basically you must download the ISO LiveCD, burn it to a CD, boot from it, and make an image to another drive, usb, ssh server, nfs, etc. also the resulting image can be compressed.
I've just imaged a 40GB partition with 22.5GB used to a 5.12GB archive bzip2 compressed, it took 90mins aprox.
Slashdot Mirror
http://www.clonezilla.org/ basically you must download the ISO LiveCD, burn it to a CD, boot from it, and make an image to another drive, usb, ssh server, nfs, etc. also the resulting image can be compressed. I've just imaged a 40GB partition with 22.5GB used to a 5.12GB archive bzip2 compressed, it took 90mins aprox.