Preloader...Yes another preload Q .. but this is Advanced :D (I think)

Im after a way of doing a preloader, that just doesnt load like a bar, but loads in a circle, so the preloader will draw a cricle, around my logo. If you dont know what i mean ive attached a image below…

If youk onw where i could learn how to do this or you know where i can get a script to do this, please could you post it?