Windows 7 is supported in AutoCAD 2010 (and 2011 and higher) and Inventor 2010 (and 2011 and higher). If you want to install and run older versions of AutoCAD, LT, or Inventor (2009, 2008, 2007, 2006, R11…) in Win7, you can use the virtualized “XP Mode” available for Windows 7 Professional, Ultimate and Enterprise (both 32-bit and 64-bit).
To use the Windows XP Mode you will need a CPU hardware support. You can detect the HW virtualization support in your processor with the utility havdetectiontool.exe . The Windows XP Mode add-on (application) can be downloaded from the Microsoft web. Then you can install the tool through Windows Virtual PC > Windows XP Mode.