a new hard drive should only set you back about £35.00, and it would be easier just to buy your own (legal+ official) copy of windows so that you have it for future use as well(about £50.00)......forget about warranty as once the foil wrapper on a hard drive is opened that's the manufacturers warranty finished, they only do an until opened - from the date of manufacture warranty as its classed as a consumable memory product just like a blank CD by them......getting a replacement or money back will be impossible.....and too much hassle for nothing...you can get a replacement for faulty RAM memory but not for a Hard drive as its a magnetic drive whereas RAM is solid state(not moving parts) and is classed differently....
on a side note, solid state hard drives (SSD-Solid state Device) hard drives are available now and not overly expensive, you will find them at misco online and in Maplin Electronics shops as well as other places....and they are highly reliable as they don't have any moving parts so are not easily damaged by bumps, whereas rotating Hard Disk Drives are very easily damaged by even minor drops or bumps while they are in use (powered on and rotating)
I am trained and experienced/qualified in IT repair, if you want to ask about how to fix your own computer, pm me on here.
