2 For many years truecrypt was used very successfully to password protect data, but the developers decided that they would no longer continue to develop and support it; the effect being much like that with Windows XP when Microsoft stopped developing it and supporting it.
3 Bearing in mind that Win XP is no longer a safe operating system to use on a computer that is not isolated from other sources of data (and that includes the internet, flash drives etc etc.) then truecrypt may serve your purpose, however please do your own research on this, and to get you started have a look here: https://www.grc.com/misc/truecrypt/truecrypt.htm
4 Backing up is a wise step for any user to take, but please note that a backup that does not have at least one copy kept safe offsite and on removable media, is no back up at all….. I usually recommend at least 3 copies on separate media and usually recommend disc images, with the creation of an emergency boot disc as well)
Do remember that with powerful encryption tools, its vital to keep passwords safe, if you lose/forget your truecrypt password then the data can be regarded as "gone"
yes I know xp is unsupported nowadays but the only time I am likely to use it is if this PC fails and I need access to the internet temporarily, guests that stay tend to have their own laptops etc.
Using the xp PC will be my third back up, I have an old hard drive that I use externally and that is stored in a fireproof safe away from the main part of the house.
I had a quick read on your link and that should be sufficient for my needs.