Wow. An actual Java applet. It's like 1998 all over again. Too much for a simple graph. You should consider replace it with flash... or even pure Dom/Javascript, like these guys: http://www.genoom.com
thanks yeah, there is a flash version about ready to drop. it is overkill for the simple graph, but when we map all web 2 startups in boson. or compare two VC to see if they have invested together in the past, being able to zoom and pan will be more useful.