Hello folks,

Need your advise on choosing a nice and free information graphics software for windows. I'm particularly interested in plotting simple Cartesian graphs of functions and differential equations.

- I'd love to be able to plot tangent lines to a curve.
- Would be great if it let me paint bounded areas under a curve.
- Even better if it drew partitions illustrating Riemann sums.
Mustmake use of antialiasing.Mustbe able to export to png, gif or jpg.

This is software I'll be using as an educational tool both in-class and as a means to compile study material for the students.