need a graphing program

anyone know of a graphing program that i can plot points on 2 axis and run a best fit slope through it? catch is it has to be able to make the graph on milimeter graph paper (like the graph needs to be that accurate). and don't say excel...that doesn't cut it.

thanks

There are some websites that will do linear regression, but I don't know how accurate they are... probably not very. Use a graphing calculator and do it by hand.