Robhi -
Sorry I missed this post the last time I was on the net. Hood has given you good advice - is he says the drives you have bought also do step and direction pulses, then use the drives you have bought to get started, You can wire them in parrallel if you wish, the drive is linited to 2.5amp so will not give you full speed/torque but will be better than wired in series.
The drives I use are the Gecko 201 - the simplest one you can buy. If one of your drives fails, then buy a Gecko to replace it.
Best of luck