This java applet can be used to determine whether or not the means in two sample populations are significantly different.
This applet performs the Student's t test on two sets of data, and reports the average and variance for both sets of data, the t score, degrees of freedom, and one and two tailed P values.
As mentioned on the home page of this resource "This site presents workbook-style, project-based material that emphasizes real world applications and conceptual understanding. This material is designed to give students a sense of the importance and allure of statistics early in their college career. By incorporating many of the successful reforms of the introductory statistics course into a wide range of more advanced topics we hope that students in any discipline can realize the intellectual content and broad applicability of statistics."