Making A 2-Speed Fan Controller

[xGuyFawkes]

So I know as much about wiring and electronics as my "high school education" (cause I've learned more from YouTube in an hour) gave me. Granted I do know a bit, I am trying to simply make a two speed fan controller that does nothing but change the voltage from 12v to 7v (I dont feel a need for 5v as my computer runs a little warm most days anyway). So I drew up a very very basic diagram on Windows Paint, and would like some feedback or help if this will not work.

 

[xGuyFawkes]

Also, in this diagram, a 2-position switch is being used with the ON-ON configuration. If a 3-position switch is used, ON-OFF-ON, would the fan be turned off when the fan is dead center? I am assuming so but want to double check.