Nexis, dunno about software and programming, but there is a high-school maths formula for working out orbits, if you're up to it:

T = 2 pi sqroot(a^3/GM) Where T is the orbital period in seconds, a is the semi-major axis (radius for a circular orbit) in metres, G is the Gravitational Constant (6.7 e-11) and M is the mass of the planet in kg.

It'll keep most astrophysicists happy.

You could use this for both the planet around the star and the moon around the planet and then figure out the phase angles using a spreadsheet, but if you're looking for a 'point and shoot' version, I can't help, sorry.

However, I'm sure such software exists - try googling for 'orbital calculator' or 'orrery calculator' or something like that. There is probably some online thingy that will crunch the numbers for you.

Edit: This looks like a simple one:

http://www.calctool.org/CALC/phys/as...y/planet_orbit

Hope that helps.