Earlier this week, Microsoft began
restricting access to Windows operating system updates to non-pirated copies of Windows XP. To enforce the change, the software giant added a validation check to its update process in which the Windows Update site verifies that your copy of Windows is valid.
The validation check was
cracked in less than one day.
With one line of JavaScript.
[CNET News.com] Piracy-check mandatory for Windows add-ons
[Boing Boing] Microsoft "Genuine Advantage" cracked in 24h (via
Download Squad)