The only available versions of AutoCAD for Windows 7 are AutoCAD 2010, AutoCAD 2011, AutoCAD 2012, AutoCAD 2013, and AutoCAD 2014. If you have AutoCAD 2009 or below, you can try to install Windows XP Mode and run the application natively in Windows XP without any compatibility at all. Download and install Windows XP Mode, then you will have the possibility to run the application in XP Mode using right click on the executable file.
Fore more information regarding compatibility, you can browse the Autodesk official page.