How to evacuate a home computer

What is the most sensible way to evacuate your home computer?
1. take just the CPU unit;
2. make a back up on CDs and take the CDs;
3. back up the main CPU on an external drive and take the external drive;
4. make an image of your CPU on an external drive and take it.

With hurricane season upon us and some of you may have been affected. What is the best method?