Not all of our PCs come with operating systems. The best thing to do is to look at the spec of the PC you have ordered and see if the Operating System is listed on the spec or whether it says "None". If you have bought a PC without and operating system then it will come with no software apart from the drivers and any additional software you may have ordered. We do provide you the option to buy our PC's with the operating system pre installed and offer Windows Vista / Windows XP and Windows Media Center.