If you're doing diagrams for internal use and know the chances of them being used with external parties is slim-to-none, go ahead, play with toys like dia.
Rather strong opinion...
PDFs are almost 100% acceptable, with a few losers left who won't install a reader.
Hey, wait a minute! DIA can export as Postscript and ghostscript can turn those into PDFs. Therefore, you have contradicted your earlier assertion. By the way, there are other possibilities with DIA as well. It is scriptable with Python so you can do useful things like validate a diagram against the network. http://www.gnome.org/projects/dia/python.html There is also diacanvas2 which allows you to integrate the DIA drawing canvas into your application. http://diacanvas.sourceforge.net/ With diacanvas and python, you make an interactive network diagram and bundle it into a Windows .exe file to distribute to the sales force so they can do stuff like zoom in and out. Fact is, that the availability of reasonably featured and stable Open Source software has mushroomed over the past few years. --Michael Dillon