A Pro/E part is a 3D model file and most AutoCAD .dwg files are 2D drawing files. You cannot go from 3D to 2D without creating the 2D in ProE (ProE drawing). So, you could go from 3D to 3D by trying to export .prt to .iges and bring it into AutoCAD 3D (if ACAD R14 has that capability) or by creating a ProE drawing (as suggested earlier) and then Save As to DWG.
I am betting that you could either create or buy a script (either Pro/Toolkit or Jlink) that would dump .prt files (on mass) into a standard drawing format with basic view template (having standard view layout) and then export to .dwg (either as part of the script or not). If you can mass create the .drw from .prt, then you could use Pro/BATCH to generate the .dxf, .dwg or .iges as needed to bring in to AutoCAD (or other programs). I am betting this is both not difficult to develop but also was already created by someone.
You might want to try asking some on some of the developers forums.
Good luck.