Teresa's answer is great - of course!
I would just add, that using rsync is a much better way to copy (backup) from one place to another because a) it only copies files that have changed, b) the data is compressed, and c) if using SSH it's encrypted.
There is also something called GIT (http://git-scm.com/), which is more of a developers tool, and quite difficult to understand at first I think. However it might be worth looking at because my understanding is that GIT, rather than CVS, will be the prefered way to install and update Moodle in the future.
Stu