I doubt you'd need spacers. Work out your chainline on paper then work from there, it depends on the crankset, Bottom bracket and the rear hub. http://www.sheldonbrown.com/chainline.html
Use info from here to do some measurements.
Also, look at the hub you just bought, the lockring goes on the smaller set of thread, it keeps the sprocket on, so is crucial to you being able to ride on the road.
I doubt you'd need spacers. Work out your chainline on paper then work from there, it depends on the crankset, Bottom bracket and the rear hub.
http://www.sheldonbrown.com/chainline.html
Use info from here to do some measurements.
Also, look at the hub you just bought, the lockring goes on the smaller set of thread, it keeps the sprocket on, so is crucial to you being able to ride on the road.