Dear Rajiv

You will require first to extract the entropy/free-energy from xpm file then you can plot it with tools such as gnuplot, mathematica or matlab. for details look at the end of this page:

http://nmr.chem.uu.nl/~adrien/course/molmod/analysis2.html

Thanks for your answer. The link gives Mathematica notebook.

GNU plot is easier as it is freely available. Do you have experience of preparing energy-landscape well using GNU plot? If yes, I want a rough script to do this.

I recommend Mathematica to do this as script is already available in the above metioned link