Arconis True image will work great. If you also get the Arconis Disk editor/director and create a bootable resque cd you'll be able to backup and restore OSX, Vista, Windows XP, Linux, BeOS without a problem. From USB2.0 external harddisks as from internal harddisks as from Firewire harddisks as from ATA optical drives. At least that is my personal experience with Asus P4P800Deluxe based desktop system and Acer Travelmate 290LMi laptop.
The bootable resque cd will not work on a real intel Mac though. Although it is possible to use the software when running XP or Vista on a real Mac and backup either partition!
I still have no nice way of getting a bootable G4 compatible system/restore disk for my PPC Mac.