I'll chip in here because I'm a research student and I work with a stellar evolution code (the Cambridge STARS code) more-or-less daily. Regarding some of the comments to the question, stellar evolution is actually quite fast, depending what code you use. Certainly, it isn't like hydrodynamics or N-body simulations like those used in galaxy formation/evolution and large-scale structure simulations. I can simulate a Sun-like star reasonably accurately from before the main sequence to core He-flash in probably less than 10 minutes with a fairly standard machine (single 3GHz Intel core, about 400MB RAM is used). Here are two links for software pitched at distinct levels.
Richard Townsend of the University of Delaware created this webpage which allows you to specify initial conditions for your star and then emails you the results. I have never tried it but I believe it's based on the same code I (and many others) currently use. The output is ASCII text so you can plot it with whatever. I think the author provides some IDL scripts but its proprietary software. You could use, say, gnuplot instead.
If you want a more advanced code, your best bet is probably MESA purely because it's easiest to access. MESA is a fully-fledged research-grade code. It's quite big (code with input data is about 3GB) but very robust. I recommend going through the materials on the website if you're interested in getting it running. It's mostly maintained by Bill Paxton and makes use of much more software engineering practice than other codes. It also comes with its own visualization plugins for pgplot, if you have it.
Hope that's something like what you were looking for!