Corel CorelCAD 2013 Upgrade (Windows and Mac): * AutoCAD DWG 2013 support * More OS support: Windows 8 and Mac OS X Mountain Lion (10.8) * Native 64-bit Windows support * Align viewport tool * DGN underlay * Windows 32-bit version: Microsoft Windows 8, Windows 7, Windows Vista or Windows XP with latest Service Pack; Windows 64-bit version: Microsoft Windows 8 or Windows 7 64-bit editions; Mac: Mac OS X v10.5.8 (Leopard), v10.6 (Snow Leopard), v10.7 (Lion) or v10.8 (Mountain Lion)