I being using a 2803 to play with the LED's but when it comes to controlling them at the time we need to do so it might end up proving to be too slow, which is why I'm considering to use a highspeed mostfet to do the job. As far as running the 3 phase on the HD, you need a pull and pull solution like the l293, but you will likely run into the same problem fortunados ran into which is the Arduino would be busy doing both the pulses for the motor and the LEDs at the same time. Unless you are considering to use a 2 Arduino solution to do all separately, I recommend you also look into the 5140 which takes care of all the phase pulses without any need for logic involvement other than a 5v high from the micro controller. PM me your info if you like so we can get in touch.