I found Retrospect Express to be cumbersome and difficult to work with. Since you do have FW, and you are running 10.3.9 I wholeheartedly recommend
SuperDuper. It is a fantastic disk cloning tool that will exactly duplicate your internal HD on your external FW drive - and make it bootable. The first clone will take a while, but with the registered version you can make incremental clones which only updates the clone to reflect changes since the last clone. It does my 320GB drive in about 15 minutes after I add a few GB of music to my iTunes library.
I find it invaluable especially when applying OS updates and make other major system changes - like when I upgraded my hard drive. I cloned my old 160GB drive, replaced it with the 320GB drive, then cloned back to the new internal, having my Mac exactly the way it was before, but not with a new larger HD.
There are also free cloning utilities, like Carbon Copy Cloner and LaCie's SilverKeeper, but I like SuperDuper better. It seems faster, and it was the only one of the three that worked with Tiger from day one. The other two needed updates that took weeks to come out. I know they are free, but I couldn't wait without backup software.
I get no kickback from the guys who make SuperDuper. I am just one of many delighted customers who use it everyday. It has never let me down.
