program for viewing MD

 I look for a graphical program to visualize MD. The program should be as simple
 as possible. It is for my students that write their first MD code. The input
 should be as simple as possible ,eg.
 atom_type, x,y,z
 for some 1000 steps, system consists of max 1000 atoms. It would be nice if it
 could color
 atoms using kinetic energy, but this is not very important. It does not have to
 have advanced graphics -
 spheres or crosses would be OK. It has to run on SGI Indy IRIX 6.2 R4400 old
 It should also be for free ...
 I tested VMD and MOIL-VIEW, however they are to complex (and I don't know AMBER
 trajectory format). It just should show my student the behavior of system.
 Any suggestions ? (|:-)