Finally! Somebody managed to write down the very same tasks that I have been doing when I was still managing servers for my department. Whilst it is easier to back-up a partition, the how-to provides enough information one needs when moving to a new server.
The /etc/passwd, /etc/shadow, /etc/group, /etc/gshadow, /var/spool/mail and /home are the minimum file/subdirectory that you need to back-up. If you have very complex server configuration, most of the files are in /etc. Just select the files that apply and then save it.
Personally, I find it easier to migrate on Linux than on Windows. How about you?