Please, note, as ever, that I'm not a native English speaker, so maybe you can find some mistakes in the language of this tutorial.
Sometimes ago I've made a guide (http://fabuland.wordpress.com/2010/11/29/formattare-un-pc-windows-per-rimettere-a-nuovo-il-software/) to prepare a computer for primary school work. I've decided that it could be useful even for teachers that can't speak Italian, so I try to translate it.
What you will need:
- a computer with minimum requirements for Windows XP (see here: http://support.microsoft.com/kb/314865/en-us)
- a valid serial number for Windows XP
- CD of the third parts components (but in the most of the cases you should find the drivers on line)
- an Internet connection