Microsoft Mathematics 4.0 is a free mathematics program from Microsoft (if you couldn’t already tell that from the name) for Windows. It is definitely a better upgrade to the standard windows calculator, and keeps a notebook of calculations/graphs. It is more geared toward students, but can be useful for a general graphing calculator for anyone. It can also be used with a tablet computer and stylus to accept written input.

Microsoft Mathematics provides a graphing calculator that plots in 2D and 3D, step-by-step equation solving, and useful tools to help students with math and science studies.

Microsoft Mathematics provides a set of mathematical tools that help students get school work done quickly and easily. With Microsoft Mathematics, students can learn to solve equations step-by-step while gaining a better understanding of fundamental concepts in pre-algebra, algebra, trigonometry, physics, chemistry, and calculus.Microsoft Mathematics includes a full-featured graphing calculator that’s designed to work just like a handheld calculator. Additional math tools help you evaluate triangles, convert from one system of units to another, and solve systems of equations.

http://www.microsoft.com/downloads/en/details.aspx?FamilyID=9caca722-5235-401c-8d3f-9e242b794c3a