Dave.. from what it looks like that USB controller looks good.. but i think u'll need a 4-pole stepper for it to work.. whereas from memory the 12v stepper at jaycar(cat. YM2751) is a 6-pole. Also.. bear in mind that the phases and wire-outs can be different for steppers.. which means it may be some fiddling with either the wires or code to energise the poles in the right sequence to get the motor to turn. But.. definately doable as a project!
As to the tracking project.. wildcard have usdigital encoders quite cheap
was thinking about using their encoders in the DSC box project.. but have decided to push the DSC project back and take some steps into imaging.. by getting a webcam and modding the **** outta it.
still deciding on the quickcam 3000 or a toucam.. as I'd like a toucam.. but since it's gonna be a 'project' cam.. maybe better to go with the cheaper 3000 so it doesn't hurt so bad when i break something
el