I was wondering if you hit the "de-authorize all computers" button on iTunes store, will it erase all your memory on the computers? Or the downloaded CD content? Because I can't afford to lose all my CD content in my iTunes library.
No to both questions. Back it up anyway.
How do I back up everything? I have 3 computers and 2 more that I no longer own. And they all have something different on them. How do I back up each one and have access to it when I re-authorize?
Check this article:
Back up your iTunes library by copying to an external hard drive
Retrieving data ...