Among others, Microsoft Mathematics has the following tools:
Equation Solver. Provides step-by-step solutions to solve equations.
Triangle Solver which can be used to investigate and solve problems about triangles.
Unit Converter which converts measurements from one unit to another.
Grapher which can plot 2d or 3d graphs in the Cartesian plane/space
Ink Handwriting Support, which supports handwriting for Tablet PCs.