I have a full windows simulation of the Earth to Mars trajectory on my
website, with free downloads. No experience in orbital mechanics is
necessary.

Bar X Software
http://www.bar-x-soft.com

It's written in Fortran and the Windows GUI was done with
Winteracter. The routine is accurate to 16 significant digits, and
was done with a Runge Kutta 7/8 integrator. The unzipped routine is
less than 3 megs and it takes only a few seconds to complete the
analysis ~ finding the optimum trajectory with the inputs given. The
best I have done so far uses 25% less energy than a Hohmann (there are
a dozen variables you input, if you want). Many user options that can
be selected and input, then the optimized trajectory is calculated and
printed out on the screen, all the raw numbers for each step of the
integrator are available as well. There are help files and plots
showing how the optimization routine itself works. All of this was my
Ph.D research at Texas, under the late Roger Broucke, a famous
researcher in Celestial Mechanics (and a real computer nut - you
guessed it, a Fortran fan!)

It's a fun program and very educational ~ makes you see just how hard
it is to reach Mars!