Kev - mudbox 2009 and 2010 have the ability to show the normal map on the model (lowpoly) in realtime, and then you can paint diffuse and specular on it - an easier way however is to bake a cavity/ambient occlusion map an use that texture as the first layer on the diffuse, therefore using it as a guide to painting..... - i…
Do any of the tools for painting on 3d models (Zbrush, 3DCoat etc) allow you to paint on a model that has a normal map shader on it, so you can visualize the final look more easily and paint a diffuse map that matches the normal map and such?
If you've got the extended additions of CS4 (CS3 as well??), you'll have a 3D viewer mode, which you can add diffuse, specular and normal maps onto a .obj model. Although the normal maps on the model dont look intense enough (can hardly see there's a normal map applied, but it is there).