But the major question is, could you really rely on Windows System Restore?
Sure.
I for one won't rely on system restore, many people think it is some sort of magic bullet that will take you back to a point in time where 'everything' will be as it was.
The truth is a different story, it doesn't cover all files nor all areas, so there the unforeseen/unexpected consequences of using it. The major problem is that the user doesn't know exactly what is covered by it. It isn't unusual to find that the restore point chosen by the user fails so another has to be chosen, etc.
For me it is the unpredictability of system restore allied with the uncertainty of exactly what it does cover that made me seek out an alternative. That alternative for me has been hard drive imaging software, it is predictable on what it covers and for me in well over 8 years has never failed me.
I run a full image backup every week (keeping the last 6 copies) saved to a second hard drive. I have a small program called mirror that I use several times a day to backup more volatile data, emails, bookmarks, .doc, .xls, image/media files, etc. etc. If you don't want to lose it back it up and often.