Hello Sir, I""d like to inform the optimized specification for CADian 2012 as listed below. . O/S : Windows짖챌 7 ( 64bit ) . CPU : Intel짖챌 core짖창 i5 . Memory : DDR3 8 GB Memory Or otherwise, it""s recommended to use CADian 2012 with Window7 - 64bits, i5 and 8 GB at least. * As you know, Window 7 needs much more memory. Thus, set more RAM as much as possible. If your system has Windows XP, please use CADian 2011 for the time being. We will improve CADian 2012 for Window XP, too. * You can get CADian 2011 at your email. Regards, CADian Soft