Any of
these will do.
Do you want a 5400rpm (slower but quieter) or a 7200rpm (faster but louder) drive? WD Scorpio Blue is a good 5400rpm drive, while WD Scorpio Black is a good 7200rpm drive.
Also, I'd recommend getting an
external HDD for backup; so it'll be easier to recover all your files once you swap the hard drives.