Just a few years ago, one could expect little more from a handheld computer than a convenient means of storing and retrieving data such as phone numbers and to-do-list items (Brooks 2002). Times have rapidly changed and computers have changed to give the user more ability whether it is a home pc or a handheld one. Each year it seems Microsoft is updating and changing Windows. What is an operating system? How does Windows XP differ from Windows CE? Windows XP, CE or Linux operating systems, which is the best? Why? How do they compare and contrast? This paper will define operating systems for computers and compare/contrast Windows XP, CE and Linux Operating Systems.