Updating xp to 7
First, locate the HKEY_LOCAL_MACHINE folder under value just needs to change - it doesn't matter what it's changed to. Note: In the command above, the only space is between "exe" and "/a".
Take note that the there is another difference here between the Lync and Communicator clients.
Changing your Windows XP product key should take you less than 15 minutes.
Important: Please be aware that changes to the Windows Registry are made in upcoming steps.
For standard 32-bit operating systems the registry path below is the same regardless of the client versions (OC 2007 R2 with July 2009 update or Lync 2010 RC) but previously 64-bit operating systems running the 32-bit only OC 2007 R2 client had to have the setting created under the Wow6432Node policies key.
The main reason you might want change the Windows XP product key is because your key is pirated or otherwise incorrect but you don't want to reinstall Windows XP to activate your new legal product key.