Hopefully a simple yes or no answer to a question.
I know you are permitted

by Microsoft to make 1 back up of your OS.
Having been caught out once before by damaging my W2000 OS disk and then finding my hard drive dying on me leaving me bereft of computer, I don't want to be caught again.
I now have a new PC and want to make a copy of my OS. Is it just a simple matter to do an ordinary copy or is it more than that? Someone told me that it has to be bootable? -- but isn't the original like that anyway?
Does this make sense? Am I asking too many questions? Is the answer 42?

Thanking you in anticipation.