I'd like to add this suggestion, from my recent experiences:
Make sure that you also have a plan as for what you are going to do if the pc dies and you have 3 perfectly good hard drives full of data. Be sure your backup PC can handle those drives, or your data could end up being held hostage by the hardware and/or OS limitations of your backup machine.
My old pc is no longer suitable as a backup machine. Back in the days when my main PC ran the same OS as the backup machine and all my HD's were PATA, FAT32, and 80G or less, it was fine, but not any more. None of the hard drives from my main pc can be used with it. Can't use SATA in it and can't use large HD's over 137G (OS limitations). And all those DVD's I burned are a bit useless when the optical drive in the backup machine is a CD-ROM that won't read burned CD's, nevermind DVD's of any type, burned or not. And it doesn't have (and can't have) USB, so any external drives are also useless.
So either make sure the old pc you keep as a backup machine can handle the hard drives from your main pc (and your burned disks), and buy/build yourself a low end machine that can, if it can't. This goes for the OS on the backup machine as well. Make sure it can handle what you have.
I am sure glad I used offsite storage I can access online, for some of my data that wasn't already copied to the backup PC, that doesn't rely on hardware or OS for me to retrieve it. It was the smartest backup I ever did.
Oh, and for you laptop users, if you are relying on a desktop PC as your backup machine, make sure you have a way to use that little HD from the laptop with it, and if you are relying on another laptop as a backup machine, a way to connect a 2nd little laptop HD to it.