You know, there is a large amount of imaging software. A year ago I was searching and compare many of them, for several days, and stopped at Acronis True Image. I think it's the easiest and most convenient backup software
. I just create an exact image of the whole HDD, save it on "D" drive and another copy on DVD, also you could make a bootable CD. It takes reasonable amount of space due to highest level compression. Whenever I want, I could easily restore image, it takes me about 10min. And you needn't re-activate or reinstall windows, as image contains all apps and data!