System Requirements
From AutoCAD 2009 Readme
Before you install AutoCAD 2009, make sure that your computer meets the minimum hardware and software requirements.
Whether the Windows operating system is the 32-bit or 64-bit version is automatically detected when installing AutoCAD 2009. The appropriate version of AutoCAD 2009 will be installed. The 32-bit version of AutoCAD 2009 cannot be installed on a 64-bit version of Windows.
See the following tables for hardware and software requirements.
NoteAdobe Flash Player is
no longer installed by default. If a suitable version of Flash is
not currently installed on your system, a message requests that
you download it from Adobe’s website. If you do not have Internet
access, you can also access the Flash installer on the AutoCAD 2009 product
media.