You can download an .iso image of Ubuntu or Ubuntu Server here: http://www.ubuntu.com/getubuntu/download.
Ubuntu can be run directly from the cd, or installed to the hard drive. Ubuntu can be installed alongside your existing operating system for dual booting purposes.
Try it. You'll like it. I use Ubuntu on notebook, which the kids use for internet and school work use. (there are plenty of free games and educational software that you can add too!



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