Currently graph.tk only supports modern browsers that natively implement <canvas>. There's a clever Internet Explorer script that uses VML to simulate <canvas> called Explorer Canvas that's pretty legit: http://code.google.com/p/explorercanvas/
I tried explorer canvas a while ago, but there were many other IE-bugs in the basic javascript. Now that the javascript is cleaned up a bit, it should work, and we can give it a try.
Currently graph.tk only supports modern browsers that natively implement <canvas>. There's a clever Internet Explorer script that uses VML to simulate <canvas> called Explorer Canvas that's pretty legit: http://code.google.com/p/explorercanvas/
Seems worth a try.