For those of you who don't know "Open Source" means free software. It's stuff you can download off the Internet and install for free. Up until a few years ago most of this stuff was small, support type stuff. But now we have Operating Systems and major software bundles out there. In fact there is so much great stuff out there that I am currently designing a class for my grad students based entirely on open source software.
This has become important in light of the failures of Windows Vista and Apple's proprietary business model. The best and most user friendly OS out there is Ubuntu. Free and relatively easy to install. An added bonus is the Linux code its built on- way less viruses. An advanced user could even partition their hard drive and run Ubuntu as their primary OS, and keep Vista for things that only run with Vista- an oxymoron, since even basic Microsoft apps have bizarre issues with Vista. The other major software my students will be using is Open Office, which basically mirrors Microsoft Office and is even "supported" by Office, so to speak. I have been showing many students this suite and they have loved it. For anyone this side of an advanced user, Open Office is all they really need. It runs beautifully and its free!