Thanks Adam878639 for this article :P Microsoft is planning what could end up being quite a shock for the Windows XP warez world, and what currently looks to be one of the most amazing moves made by Microsoft since Windows Product Activation was introduced.
Currently, Microsoft is in the works of completely rewriting the algorithm for the way Windows XP Corporate keys are generated, and is rewriting the code for Windows XP to recognize this new algorithm. This new code will be an added 'feature' of Service Pack 1 due out later this year.
At the present moment, an upgrade to Windows XP SP1 from Windows XP with no SP installation will not give any problems or errors about an invalid CD-Key on a corporate version of Windows XP. This is because the new algorithm feature has been switched off in SP1 upgrades. To get to see this new feature, you would have to slipstream SP1 into the Windows XP installation media and setup Windows. Once you've reached the CD-key, no current Corporate Windows XP key (none of the 75 that we've tried) will work, as they are all invalid. Even if a corporate key is managed to be found, the chances of it working when SP1 final comes out are slim to none, as Microsoft is rumored to 'still be working on the algorithm for SP1 for Corporate customers'.
So why is Microsoft keeping this a secret? To put it mildly, they are a bit perturbed that warezers have been able to exploit the corporate edition of Windows XP to completely bypass WPA. They are planning to keep it a complete surprise until SP1 final has been released and shut down as many warez users from using Windows XP as possible. They know if it's made widely known what they are planning, nobody will upgrade to SP1 until an appropriate patch has been made.