3D Analysis of peptide - (Jan/17/2001 )

I want to do 3D analysis on a 500 aa long peptide(Sequence already known). Can you tell me where I can down load software to do this. Thank you very much.

Would You like to try this URL: http://www.expasy.ch/swissmod/?

This model system need an existing template of which the 3D structure is already known. And your peptide need to be had a homology with it at least 25%