Inventor has plug-ins for 3ds max that allow a user to directly import .ipt and .iam files. Inventor 5 works with 3ds max 3 and 4. Inventor 6 also works with 3ds max 3 and 4. You must install sp1 for inventor 6 and download the updated plug-ins for 3ds max in order to import files into 3ds max 5. Both of the updates can be found at
http://support.autodesk.com/enu/Homepage.asp
On the left side of the page click on Download Updates and Drivers
In the center screen
Product: Autodesk Inventor
Release: 6
Category: Updates and Maintenance
Click on GO
you need
Autodesk Inventor® 6 Service Pack 1 (All versions)
and
Updated Autodesk® VIZ and 3ds max™ Plug-in for Autodesk Inventor® files
Follow the instructions found in the readme files.
Max imports the files as a perfect editable mesh. Assemblies import as individual editable meshes.
I hope this helps,
Dennis