That's what these diagnostics are for. The good news is this can be a cheap part.
Recently I decided to defrag my disk drive (Dell 4100 37 Gig capacity) and after that was completed, everytime I boot my system Scandisk starts running and it takes forever (about 10 hours) to complete so I cancel out everytime. I contacted Dell and they asked me to diag the disk by bringing up system diagnostics and pressing 'ctrl-alt-d' (NOT 'ctrl-alt-del') to start hard disk diagnostics. The thing ran for a minute and came back with a 'RC=7' error code. The Dell agent said my hard disk is about to die and I need a new hard disk. Is this true? My compueter runs albeit erratiically but it is usable. Can anyone help me with this?