Trying to use the built in Mac OS X VNC server was slow and unresponsive.  To speed things up, we switched to use the Vine Server (OSXvnc):

http://sourceforge.net/projects/osxvnc/

The client we are using is Utra VNC:

http://www.uvnc.com/

There is also TightVNC:

http://www.tightvnc.com/

They both seem to work about the same.  If anyone has a preference of one over the other, let me know.