I have been using the free software Veeam Agent for Windows, it's from Swiss company Veeam, they are big in corporate backup solutions. Veeam Agent for Windows is their free "endpoint" backup solution and you can use it backup entire computers, volumes or on file level. I use it to backup selected folders, including Cakewalk/Sonar projects, on a weekly basis to an external USB-drive.
It allows you to keep a selected number of file versions and it allows you to easily use two different USB-drives, if you have another drive you keep off-site and update only occasionally.
It's been rock stable, easy to use and a lot better than some backup software I bought... (I'm looking at you, Genie Backup Manager Home... )