Harddrives

Well basically my harddrive on my laptop has given up the ghost as they say. Its still working just very slow and making an annoying grating sound followed by a beeping sound(not an actual beep just closest description) I have a feeling its a few weeks out of warrenty and I cant find the invoice to confirm it. Would anyone be able to suggest where I could buy a new one. Its a removable sort for a compaq pressario R3000, dont give me some rubbish about the thing being crap Until this its been fine and no I cant afford a new one. Sorry for the rude disclamers but I have already heard those and its not an option. I might just about be able to scrape together a new harddrive but I cant find where to buy it. 
