Booting from external disk drive

[xairbusdriver]

I bit the bullet, backed everything up (sigh) and did it the right way.

Does this mean a simple re-use of SD, without using the "Copy New..." feature?

OR

Does this mean backing up the important stuff ( do we ever back up unimportant stuff?! ) on the external and reformatting the partitions?

One is certainly much easier! And I have a 250 Gig, in 3 partitions external to back up. Of course, I could simply back up the documents...

Thanks!