Experience with Carbonite? Other choices.

I use the Free open-source Truecrypt. Relatively easy to setup. And have multiple encrypted containers including one for Dropbox files, which in itself is within another encrypted container for local protection. All of which mount with one Truecrypt key at Windows login. My advice would be to name your containers appropriately, so they can be easily identified as they act as normal storage drives when mounted.

My Dropbox Truecrypt container files are available on all my Windows, Mac, and Android devices.