Ubuntu is a very solid OS, that's more appropriate for a moderate level computer user, as it does require some command line functions, even with a robust GUI. Still, a few growing pains from now, you'll wonder why you ever went without it. I love the OS, myself, and use it alongside Windows 7.
Ubuntu is stable, reliable, and pretty damn fast, too. It uses fewer resources than most modern fully realized OSes, and there are a lot of programs available for it, for just about any need you might have.