MidnightCarnival, sculpting apps like ZBrush, Mudbox, 3DCoat and now Sculptris perform best on imported obj's that are low poly. The subdividing takes place inside the sculpting app as you sculpt.  That's not to say you can't or shouldn't load in a mesh that's been subdivided but for best results in those apps, it's usually low poly, quad based meshes people work with.