I ran into a similar problem last week installing an autocad application to run a cutting machine at a cabinet makers. 64 bit Windows installs 32bit stuff into (drive):\Program Files (x86)\ but a lot of applications are hard coded internally to look for stuff in c:\program files\ and the application doesn't need to be that old to do that. That particular autocad decendant I was dealing with is new to market in .au and costs $30K for the cut down version
