computer you wish to change the HDD in Please.
Firstly; Which Windows do you have?
If its Windows 95 I would personally not bother.
Going off the age based on the size of this HDD I think you would find putting a bigger HDD in would A: Not be recognised at its full size if using Win 95 or 98 and posibly ME because I have the feeling your Motherbaords BIOS is old and wouldn't realises the real size of a newer HDD.
You would also save yourself £40 ish + if you just sold the computer with the 6GB intact.
I could go on but really it would be like putting new wine in old bottles as the saying goes and not look or work too great and casue probs.