(HTTP://menza.org/2007/09/why-a-seperate-home-rocks) about why the /Home
directory on a separate partition on Linux is good, and it's totally
true, then if you upgrade to the next version of your prefer Linux
distribution (like Ubuntu, Kubuntu, Debian, Suse, Fedora etc.) all your
preference, your choice of wallpaper, your desktop theme and so, will be
there to meet you, also if you have multiple Linux distributions using
the same Desktop (Gnome, KDE etc.) and switch from one to the other,
you won't have to search where everything is, it's there where you put
it.
On a Desktop, if it's on a separate drive, then if the drive on which
the Operating System is fail, then just replace that drive, re-install
Ubuntu (or your preferred one) and your good to go.
Also if you have to send your computer for repair and the /Home
partition is on a separate drive then you can remove it, send your
computer for repair and if it's dead and ready to be buried, put that
drive with your Home partition in a new computer, and you are ready to
go.
Desktop and Laptop users, BACKUP as often as possible your data, to
CD/DVD, external hard drive or on-line storage, but BACKUP
