We have been experimenting with a cheap (15 - 20 pounds sterling) program
called 3D Landscape Design from the Microsoft 'Expert' series. This
produces some impressive results in 2D and 3D and might be worth looking
at.
Quoted number in US is (305) 567-9996 from 9am - 5pm Eastern Standard
Time (I suspect that this will mean more to you than to me!!)
Good luck
Stuart Barlow
Lecturer in Landscape Construction
Sparsholt College Hampshire