I also build my own PCs and failed to copy (backup) some pics on my HDD once before swapping mobos, only to run into problems that required a format to cure (I later discovered that I could have avoided that too but too late). Needless to say, I lost about 70 pics from a vacation. The only good thing about that was that it's a place we go to every year, so was no big deal really.
I now always make copys, either on another HDD (another PC) or burn them onto a CDR occasionally.