windows needs several megabytes of free hard drive just to run [100MB up]. you could clean the hard drive of unwanted junk to make room. A new 80GB drive costs about £50 but your old pc may not be able to run it without flashing the bios - a bit daunting if you have never done it. With an old pc you reach a point when it is not worth spending a penny on it and you go for a new one. If it is a Pentium 3 or equivalent a new hard drive and more memory are cheap options and the drive could always then be transferred to a new pc in the future.