What are you currently trying to run your CAD software on? Are you focusing primarily on 2D drafting or 3D modeling ?
Prior to 2010, PDF integration required third-party plugins and offered poor visual fidelity. AutoCAD 2010 integrated native PDF publishing with significantly smaller file sizes, font recognition, and the ability to underlay PDF files directly into the drawing canvas as accurate snapping references. System Requirements for the 64-Bit Edition Autodesk AutoCAD 2010 -64-BIT-
You could define rules like making two lines permanently parallel, perpendicular, or concentric. If you moved one object, the connected geometry adjusted automatically. What are you currently trying to run your CAD software on
The 64-bit framework dramatically reduced the frequency of fatal errors during complex operations like rendering, plotting, and boolean 3D modeling. Groundbreaking Core Features of AutoCAD 2010 Autodesk AutoCAD 2010 -64-BIT-