Need an X-based program to display protein molecules

[Pete Levinthal]

You might want to check out Xleap.  It compiles on Suns and SGI's.  It builds
models, allows 3d xforms, and displays by various parameters.  

I'm not involved with this package, but have compiled and used it.  It meets 
the requirements you set out, and is also a useful model builder.

You might try sending mail to Chris Schafmeister (schaf at cgl.ucsf.edu) to get
information about availability, licences, etc..

Pete