I too have used Carbonite for the past few months and find it works very well. I have restored several files just to be certain that all works as intended. It easy as its files mimic your windows explorer. Simple to restore files. I also have a external drive and I still use that, mostly for storage.
Incidentally, each time you add, change or delete a file, Carbonite backs it up, as well as deletes changes you make automatically. Best thing since sliced bread.