Everybody has got you covered on your main question.
I just wanted to mention something, especially when it comes to installation media, as that tends to be what people lose the most as hardware keys are required for day to day operation.
As optical media has a finite life as it is and considering most software isn't still being disseminated, as a whole, in this manner anymore, I would suggest creating ISO backups of what optical media one does have that might still want to try to use. Most current PC OSs (Linux, Windows and Mac (yes, Mac is technically a PC despite what Apple's marketing department would have one believe)) will read ISOs as virtual drives and mount and treat them as such.
This makes it far easier to backup and move, when needed, the "optical media" so it doesn't get lost, broken, and/or corrupted to prevent installation (corruption in this manner will more then likely be during the "burning" process to create the file itself).
I would suggest using burning software compared to archiving software for this method though. Burning software will give you alerts and ask for user input when it comes to potential naming changes and such things that archival software may not and everything has to be "as is" for the method to work. Especially when it comes to naming and file hierarchy structures.
Just something I would strongly suggest. Could always burn that ISO file back to a physical media if needed/desired as well.