One of the things that many schools and teachers miss out on when they think of Microsoft is the wide range of software that's free. It ranges from the things you already know (like Windows Live Messenger) to more technical applications (like the free version of the Visual Studio Express). But did you know that there are also a range of education specific applications to help teachers and students? And that these are free too?
One that's just been updated is Microsoft Mathematics, which contains a graphing calculator, an equation solver, a formulae and equations library, unit conversions tools etc (handy for old folks like me that work in feet and inches when the kids work in metres and centimetres).
The equation solver and graphic calculator allow you to take complex mathematical concepts and visualise them on the screen as charts and diagrams. And the best thing about Microsoft Mathematics 4.0 is that it is free - and doesn't need Office or anything else on your computer - just Windows.