Let's start with backing up your configuration. Want to do a small upgrade? Backup your configuration. Want to do a configuration change? Backup your configuration first, just in case you need to revert to the previous one.
There are a couple of ways you can do backups. One way is a full system backup, which will cover Windows, 3CX, your call logs, and everything you'd need to recreate your system. How do you do this? There are several ways and they all have their pros and cons.
One such way is Windows backup software—Yes, Windows has a decent backup software built-in. No, it's not the best, or easiest, but it's free. Starting with Vista and Server 2008, it's much better, as long as you want it to be backed up to locally attached hard drives. It works well, but it's not my first choice.
There are lots of third party backup software products out there. They are generally better than the Windows one, however they cost money, sometimes quite a bit, if you want to backup...