[G4] Backing up hard drive

[Richard Klein]

I'm trying to help my sister (long-distance) replace the hard drive in 
her Gigabit Ethernet.

Tech Tool Pro 4 reported 869 bad blocks in a surface scan of her Western 
Digital WD400BB 40GB hard drive.  She has an external USB drive that's 
at least 40GB, so I'll have her format that, back everything up onto it, 
and then take it out of the external case and use it to replace the 
Western Digital drive.

How can she back it up so that, after putting the replacement drive into 
the Mac she can just boot directly from it?

Thanks!
-- 
Rich