Simplest way is get some decent back-up software. There are free ones, but probably the best is Acronis True Image. You can get the 2012 version for about 25$. You can set that up to do regular back-ups, automatically, and, importantly, it's dead easy then, to recover from almost any disaster. You can set it for lots of different types of back-up, including, for your example, "incremental", which takes a full back-up, every so often, and in between, just adds what you've added, daily, or whatever you choose. It's very versatile, and so "re-assuring"