Hmm, I think Jari is right it would sound like your fan is screwed, if your harddrive was making that sort of noise then I would think that your PC would switch off while starting up. In any case if your sure its the harddrive get it replaced,
a good tip is that if cant access any files or the harddrive has stopped working, put it in the freezer, turn it back on, and transfer the files. It worked for one of my mates