You can have Ubuntu, Xubuntu, Kubuntu and Lubuntu all in the same computer

Human nature seeks variety. Ubuntu may be the most fascinating of the 4 variants but I like Xubuntu, Kubuntu and Lubuntu as well - for different reasons. However, if you have installed one, you won't be able to install other overwriting the older one. And a new installation means tons of downloads (Ubuntu first update downloads about 300-400 mb every time) and reinstallation of your favorite