Installing Windows is usually a simple (if not particularly quick or painless) process, with straightforward options depending on whether you are upgrading, adding to a new machine, or replacing a damaged edition of Windows. Exactly how you install Linux varies depending on which system you get and whether you already have Windows on your computer. However, many versions are getting more user-friendly and some can even be installed directly from a CD. Unlike Windows, there are some versions of Linux which run directly from a CD without even being installed. And because Linux is so versatile, there are even some ultra-slimmed down versions which will run from a USB memory stick.