How to reformat your hardrive

"Hey, Windows XP users: The blue screen of death got you down? Missing dll errors making you frown? Frequent software crashes leave you yearning for that fresh, new PC you unpacked with glee three years ago? If you’ve scrubbed for spyware and viruses, defragged, chkdsked and done the requisite rain dance but things are STILL wonky on your computer, it may be time for extreme action"

[ Lifehacker ]

Since all the non geeks i know are proned to want to reformat their computers every couple of months because they have a "virus" and call me when everything goes here a good artible on how do it correctly.