Creating a movie of a moving molecule?



Hi all,
   I've a quick question for you guys. I am wondering how to create a movie of
 a molecule that I have rotated and moved for inclusion in a PowerPoint
 presentation?
   Preferably freeware that runs under Windows 95, but I also have access to
 IRIX 6.3.
   Any personal experience on what you consider to be the best software would
 be much appreciated.
   Thanks in advance,
 Darren Fayne
 Get your FREE Email at http://mailcity.lycos.com
 Get your PERSONALIZED START PAGE at http://my.lycos.com