Well personnely IDK about you but I have no intentions of shelling out 200 or so for every single format/build if I did do that i'd have a pile of OSes. Now lets assume your using a older computer to type that message right there. IDK about you but I keep my OS system disk VERY safe its in a jewl case. with CD code written all over it in a closet. So if I need to reinstall it or install it on a new system I just reuse it. Plus my dad gets that kinda stuff free from work so heh never though about it.