If you just want it to go around (not worried about getting much torque or speed etc.) then you could treat the hard drive spindle motor like a very low resolution stepper motor - you just need to supply the motor with low voltage 3-phase AC. It could be a set of square waves generated in a PIC, or sine waves from a 3-phase R-C oscillator, but either way some kind of buffer will be needed - e.g. for the square waves a MOSFET bridge (or for a cheap bodge, a huge number of 74AC series logic gates in parallel), or if you're not worried about efficiency and you want nice smooth rotation, you could even use a three phase sine wave oscillator and buffer it with three audio amplifiers, e.g. the very cheap TDA2030.
If you want it to go fast, then you need a proper brushless motor controller which you should be able to find on the net (e.g. the app. notes of several microcontroller manufacturers).