Certainly sounds like the harddrive to me,but obviously do not rule out the psu.
I suggest you backup if the machine will boot into windows,alternatively,remove the drive a place in another machine as slave and try to reclaim any data.
Another way is to use an ide/sata to USB adaptor cable or an external caddy.
Looks like you may have to try another drive first,to see if the drive is damaged.
also consider the mobo could have been damaged.