Windows Media Player you can get round easily, Open Media Player 9 and then click on help, then check for player updates. You can do it from Microsoft, and simply say, no do not check the validation.

However, the latest windows update which say's

Get the latest Windows Update software.


We've made improvements to our website. To download the new version of the software and begin using Windows Update, please click Install Now.


this will actually check your CD-Key against all of the known "patched" key's available to microsoft.

The Sp1 and 2 workarounds still work as far as I know, but this latest one will not install.

Now, with regards to people doing a fresh install, then running Windows Update, I do not know yet if this new update get's installed with / after Service Pack 2