Have you considered the enthought (www.enthought.com) tool suite? The chaco2 plotting tools are quite robust. Python skills are necessary, though.
Is your dad doing the blast simulations himself or is he using data prepared by others? I'm always interested in the methodologies used, explicit FEA especially.
Hey. I have loved Gnuplot for some tasks in the past - once you DO get it working, it eats up complex datasets. But you did seem to have some totally unnecessary hurdles to get it working, and the lack of feedback means you have no guarantee it won't happen again. That sucks.
I don't think you'll like this suggestion, but you could try the Cygwin build. I use a Cygwin prompt anyway, for random command-line tomfoolery, so that isn't such a high-overhead solution for me as I suspect it would be for others.
One more minor detail, with a plot like the one you show, you can add something like:
set xtics rotate by -45
(I think) to rotate the date labels along the bottom of the graph, for readability.
I don't want to depend on a cygwin install just to generate chart images.
I'm playing with matplotlib which is less painful to start with.
Charles: I think they are doing the simulations themselves - I have no idea about the details though. 
There's at least two situations where Windows isn't located in C:WINDOWS
Those are Windows 2000 (and probably NT4 too) where the Windows directory is named WINNT, and when you have Windows installed on some other partition than C:
Commenting by HaloScan
