Glad PS3 and PC never do this lol.
Amen, brother.
As I repair the 360, PS3, and PC (along with other electronics) I can tell you first hand, they do. In all likelyhood, the drive in your PC is very simular to the 360's drive.
Are none of you reading the OP at all? I DID NOT MOVE THE XBOX INTENTIONALLY. I knocked it with my hand/arm as I stood up. I don't know how but that was enough to tip it over.
Like I said, sorry to hear. I understand it wasn't intentional (if it where, I would have used derogitory words and name calling), but its just one of those "golden rules of electronics" is to never bump or jar a spinning disk (Including a HHD).