Yeah I don't get people going through crazy numbers like 5 either.
As said before, the refurb units that are being returned here (in Germany) seem to be very inadequately tested. I'm on #5 as well, as all of the refurbs I've received only worked for a month at most (except for my current one — but then I've played a lot of Wii and now WoW). And that is not due to placing them in a cabinet / crappy power / not taking good care of them...
You shouldn't be living in this constant state of "fear" for something you paid $/€400 (what was that noise? Is the DVD drive making strange vibrations? ...)