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I have an old computer whose hard drive is wiped. The Microsoft product key is on the back, but there is no reference to which OS it is. I know it must be some flavor of XP -- is there any way to find out which one?

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Some Microsoft key stickers have a "product ID" on them, in the form of xxxxx-yyy-zzzzzzz-zzzzz. If your does, check this table. – grawity May 28 '10 at 8:10
Thanks for the table, although mine falls into the volume category and has no further specification... – ash May 28 '10 at 12:11
Did you build the computer yourself, or is it from an OEM? If it's from an OEM, you may be able to check the original ordering info online; for example, with Dell you can enter the service code on and see the original configuration, including the OS. If it was custom built, it'll be an OEM key, most likely for XP Home or XP Pro; the only way to tell would be to test it with each and see which works. – nhinkle Oct 25 '10 at 22:46
It's a Sony VAIO. Not sure if it's OEM or custom built :/ – ash Oct 25 '10 at 23:04
Meaning, did the manufacturer put Windows on, or did you? – Hello71 Oct 26 '10 at 21:22
up vote 6 down vote accepted

According to this article : Product IDs

Microsoft uses various Product IDs to identify variants of the Windows platform. A Windows product ID (currently, as of XP/2003/Vista) has the following format: xxxxx-yyy-zzzzzzz-zzzzz

The xxxxx section is the Microsoft Product Code, which in this case describes the platform, build, and version of Windows. Other product IDs with the same format, such as those found in Microsoft Office (and many other Microsoft products), serve the same purpose.

Here are some values for an English locale (the article also contains the Windows XP complete list) :

  • 55274 : XP Pro generic OEM
  • 55276 : XP Pro (upgrade)
  • 55276 : XP Home (?) †
  • 55277 : XP Home generic OEM
  • 55285 : XP Pro †
  • 55661 : XP Pro (retail)
  • 76475 : XP Home (upgrade) (?)
  • 76477 : XP Home Royalty OEM ‡
  • 76481 : XP Pro Dell OEM
  • 76487 : XP Media Center Edition 2005
  • 76487 : XP Pro Royalty OEM ‡
  • 76487 : XP Pro SP2 (retail)
  • 76487 : XP Pro SP3 (OEM)
  • 76487 : XP Pro volume license (with '640' channel ID)
  • 76500 : XP MCE 2005 (which is XP Pro with no domain capability)
  • 76588 : XP Pro x64 OEM

If the above doesn't help, the best source for definitive help is Microsoft Support.

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