I am about to sell my laptop - what do I do to make sure that every saved document, internet history, e-mail etc. etc. is wiped clean so that all I am providing is a laptop with XP please? 
'Wiped clean' and 'providing a laptop with XP' are a bit contradictory.
Did you want to clean all your records off,
without destroying your present installation of WindowsXP?
If you are willing to wipe
everything off the drive, including WinXP, that is probably easier, and safer.
One way would be DBAN.
http://dban.sourceforge.netDarik's Boot and Nuke ("DBAN") is a self-contained boot floppy that securely wipes the hard disks of most computers. DBAN will automatically and completely delete the contents of any hard disk that it can detect, which makes it an appropriate utility for bulk or emergency data destruction.
DBAN is a means of ensuring due diligence in computer recycling, a way of preventing identity theft if you want to sell a computer, and a good way to totally clean a Microsoft Windows installation of viruses and spyware. DBAN prevents or thoroughly hinders all known techniques of hard disk forensic analysis.
The cost is zero.
If you use something like this, you would need to re-install WinXP.
If your laptop has some sort of recover partition that you use to reinstall, it too would likely be gone. That means that you'd need to be able to install from CD.
Be very sure of your plans
before you use something like DBAN.
