Have you considered using the
Office Web Components at all?
I've not interfaced to them with Perl before, but as they're just COM objects it should be fairly straightforward with Win32::OLE. They're designed to render graphs and excel spreadsheets to a web client so that they don't need any office components installed - maybe this will do what you're after?
If you were on a Unix/Linux OS, I'd recommend the GD::Graph module - I've used it before and it's pretty flexible at generating any sort of graph you like. I don't believe the GD library works on Windows yet though (I could be wrong...).
