Afternoon Sam.

If AutoCad is similar to Microsoft Office, the Class Type references only the most current version installed, which would be AutoCad 2007 in your case. Fortunately, the first Argument for GetObject is Path. If you execute GetObject("C:\ProgramFiles\AutoCad LT 2006\AutoCad.exe") or whatever the path is, it should only get the AutoCad LT 2006 version.

Hope that helps you some.
Scott