What's new in version 4.0?

 Real-Time Stereo
 Vectors
 Annotation
 Smoothed Graphics
 Custom Bond Styles
 Selection & Editing Tools
 Best-Fit Plane Through Points

 Interface Improvements
 Miscellaneous

What's new in version 3.1?

 CD-ROM Edition
 Online Help
 Miscellaneous

What's new in version 3.0?

 Interface Improvements
 Building & Editing Structures
 Data Import/Export
 Display
 Transformation