How can the integrity of a system backup be determined by an ordinary user such as myself? Or is it even possible?
Buy a reputable backup/imaging program and then do a test restore. I use Acronis True Image. Works well.
Yes, well, my point is that you DO NOT waste backup space (or time) backing up operating systems or software.
Imaging your whole system every night does not "waste time" and with the decent-sized hard drives around, space is not an issue either. Last month I had to restore my whole system because Windows Update stuffed it up. This morning I restored my cousin's computer back to "clean Windows + all programs" (image taken 12 months ago) because of an unsolvable Flash player/IE issue. I transferred the outlook PSTs, Picasa Albums, Desktop Favourites and Documents and we had a "new" system within 30 minutes, and I could have rolled forward to the "bad" image if I had wanted to. That was far better than re-installing Windows, Office and the myriad updates, not to mention drivers.