As per my wife... Don't rely on iTunes. Use an external hard drive as well. You can still lose everything if just using iTunes, trust me.
I sometimes forget people are not like me. Every computer I build has the OS drive and a data drive. No other way to do it. Things like iTunes backups go on the data drive. And if you buy a data drive for your PC that is internal, make sure it is quality.
I still have most of my NANDroid backups from my Atrix 4G from 2011.