Programs for 3D viewing of biological structures?

[Antonio R. Franco]

I am using RasMol to visualize the 3D structure of biological
molecules, such as DNA and protein in my PC computer.

Is there any other program around?. I am interested in any PC  or UNIX
program equivalent to the "XRay Viewer" program you can use in the
Macintosh platform

Antonio R. Franco
University of Cordoba
Spain