Your problem is getting an Autocad to open them or open the zip file?
If you don't have Autocad or access to Autocad, Autodesk has a free viewer for opening a "special" version of these files
Look here for the viewer
http://usa.autodesk.com/adsk/servlet...&siteID=123112
This viewer needs a DWF format file and it's also on my site.... but it's hidden
Here you have the link for the DWF file
http://www.pirespreto.com/rigger.dwf
You can print from this viewer if I can remember correctly.