Fortunately, the open source community has free operating systems that meet the needs of users in all of these situations. This month we've put together a list of 50 different applications that can replace Windows XP. It's organized into several different categories. Those that are easiest for beginners to use come first, followed by lightweight operating systems that can run on old hardware, then operating systems that are particularly tailored for business users and open source operating systems that aren't based on Linux. The list ends with a few applications that aren't complete operating systems but do allow users to run their existing XP software from Linux.