I'm a primary school teacher and, in the lastet years, the only way to have computers for school is to accept them as gifts from parents or offices that dismiss them. Lots of time, these computers are full of datas and programs that aren't useful for school and maybe they're slow, full of virus and errors.
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