Its difficult to tell which version of Windows XP you or someone else is running … Home , Professional or Media Center and if it’s Retail ( Bought in a Box ) , OEM ( Bought with a new computer) or Volume License for large corporations , schools and Microsoft. Here’s a way to find out exactly which version and flavour! Click on Start, then Run Type sysdm.cpl and press enter Under the Registered To Section , there should be a 20 Digit Number The first Group of 5 Numbers Determines the Type of Windows XP , Match your code for your OS Type 55274 : XP Professional 55276 : XP Professional upgrade 55276 : XP Home 55277 : XP Home 55285 : XP Professional 76487 : XP Media Center Edition 2005 76487 : XP Pro Royalty OEM 76487 : XP Pro volume license (with ‘640’ channel ID) The second group of numbers displaus your Version , Match your number for your version Second set: 007 : retail 011 : upgrade OEM : OEM 270 : Volume License 335 : Retail 640 : Volume License 648 : Academic