If anyone is looking for a good CAD program Draftsight is an enhance clone of the venerable Autodesk autoCAD 2D drawing package but written by Dassault Systems, associated with the authors of Solidworks 3D drawing and modelling software. Twist is this is completely free other than needing to register and accept emails.
It is full blown professional CAD. Windows or Linux or Mac. (BSD presumably with Linux emulation)
Free CAD software * for your DWG files: DraftSight - Dassault Systèmes