How do you reformat a computer?

[Severance]

bugrimmar said:

wait you misunderstand. i want the best possible performance. if there is a shader version or something like that that i can't play because of an old operating system, i'd buy a new one.  i'm not just about "minimum". so is it necessary to get windows 7 for the shaders to work highest?

Performance doesn't have anything to do with OS , even if you have XP it will work as long as you do have a good graphic card.