Linux is free (As are Open Office and Libre Office), no need to buy a distro. You can check out http://www.distrowatch.com to see which distros are the most popular at the moment. Although I guess they simplify it a bit by mailing a DVD?
My favorite, and the one I use daily on my laptop, is Elementary OS. It's super simple and clean. I've even installed it for family members who only browse the web and check email, but somehow end up with all sorts of malware. Total success so far. If you can live outside of the Windows ecosystem, and don't NEED to run anything that requires Windows, then there is absolutely no reason to be running it. The biggest plus with Linux is freeing yourself of all the garbage and security issues that plague Windows.
Bought it because I wanted a DVD.
Thanks for the feedback.