I would also recommend (hint Les) that people try to get a hold of a copy of MathCAD as it the best at this kind of things (scientific formula manipulation). It does cost alot of money though.
See
http://www.mathsoft.com/solutions/ca...te/mathcad.asp
This guy exaplains heat transfer really well using it (can still see pages without the software):
http://web.usna.navy.mil/~adams/index2.htm