Boeing used Catea (spelling?) for the 777. You could use Autodesk Inventor, Autocad2000, or Mechanical Desktop, however your file sizes would be huge, and you'd need a lot of RAM. This is one of the challenges I plan to embark on soon. I want to design an aircraft in Inventor 4.0 with interior and everything. I'm not sure if my 512Mb of RAM will be enough, but I can probably do it. I'll make a post with some images when I finish it up. But it'll take quite a while.
Work Hard. Fly Right. Continental Airlines