Another option for those who want to do houses/buildings for Carrara, or any 3D application that can import DXF or 3ds files, is "3D Home Architect Design Suite Deluxe 6."

It is actually a very cool program which does a much better job than architools (which I purchased). Make sure you get version 6 or higher if you are interested, as the earlier versions had no 3ds export (the DXF doesn't work nearly as well). You can even do terrain layout (hills etc.) and they will import into Carrara with the models. You can do fences, decks -- all sorts of architectual stuff, and all can be re-shaded in Carrara.

I found out about this over at the Vue forum, and have had the application for about 2 weeks. Will cost me $15 after the rebate.