Ændring af cdkey.

To change the product ID

Backup your system state by clicking Start > Run > and typing ntbackup > Click the Advanced Mode button in the Backup Utility Wizard. >Click the Backup tab, then in Click to select the check box for any drive, folder, or file that you want to back up, select the System State

Run regedit
Browse to HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\wpaevents
Double-click OOBETimer
Remove the 'ca' part from the value
Click OK and close regedit
Click Start > Run and type in: "%systemroot%\system32\oobe\msoobe.exe /a"
Choose the 2nd option (phone activation)
Click Change Product Key (at the bottom)
Enter a valid Corporate Product Key
Press Update and close the window
Restart your computer
Verify the change

After  the workstation restarts, click Start > Run 
Type in: "%systemroot%\system32\oobe\msoobe.exe /a"
Make sure the dialog box says 'your copy of windows is already activated'
If you performed the above steps incorrectly, or used an invalid key, your system may not be able to boot. Use the F8 key to boot to the last known good configuration and retry with a valid key