There may be alternatives to spending tens of thousands of dollars for imaging
software. Lance Ladic's web page lists a number of freeware tools that may be
worth considering (http://www.cs.ubc.ca/spider/ladic/conflink.html).  One that
I've had experience with is VolVis--free, powerful, and runs on either SGI's or
Sun's.  I think you now get it by sending an e-mail note to
[log in to unmask]  There are also other software packages that are cheaper
than VoxelView, e.g. VoxBlast, and Image Volumes (...The latter is a brazen
plug, since Image Volumes is written by a friend).