OEM vs Volume license Issue

U can surely change just the product key :

From:  http://support.microsoft.com/kb/328874
1.     Click Start, and then click Run.
2.     In the Open box, type regedit, and then click OK.
3.     In the left pane, locate and then click the following registry key:
HKEY_LOCAL_MACHINE\Software\Microsoft\WindowsNT\Current Version\WPAEvents
4.     In the right pane, right-click OOBETimer, and then click Modify.
5.     Change at least one digit of this value to deactivate Windows.
6.     Click Start, and then click Run.
7.     In the Open box, type the following command, and then click OK.
%systemroot%\system32\oobe\msoobe.exe /a
8.     Click Yes, I want to telephone a customer service representative to activate Windows, and then click Next.
9.     Click Change Product key.
10.     Type the new product key in the New key boxes, and then click Update.

If you are returned to the previous window, click Remind me later, and then restart the computer.
11.     Repeat steps 6 and 7 to verify that Windows is activated. You receive the following message:
Windows is already activated. Click OK to exit.
12.     Click OK.

U can also try :
http://www.petri.co.il/change_the_serial_in_windows_xp.htm

http://www.mike-devlin.com/windows/key.htm
http://www.zdnet.com.au/downloads/0,39024478,39098244s,00.htm

download the changer sw and change the key to ur Volume key..

Hi thanks for that but,

All these solutions are for changing a volume key to another volume key. I need to change about 7 OEM keys throughout my enterprise replicated many times on the same computers.....Maybe the scripts microsoft provide can be modified to change OEM but currently i cant make it work.....

Do u wish to do this remotely, via Active directory scripts ?

Instead of that use the above steps by remotely logging in to each machine, it's of course cumbersome, but lesser than Re installing on each PC.

Id prefer to do via GP and WMI if possible as 700+ PCs would be a lot of work, plus we have remote sites

Use remote login, IMHO , via GP it's not possible , .. Infact if u compare it to work done by re installing each Pc's OS and apps, it's much easier..

There's a new XP key changer tool available from Microsoft: http://catalog.microsoft.com/genuine/purchase/UpdateInstructions.aspx although I'm not sure how you run this across 700 PC's. Maybe you could ask all your users to run it and key in your volume key.

You can not change an OEM to a volume key it will reject it every time its built into the install in the setup.ini there is something called a PID its an 8 digit number.  The first 5 digits tell how the cd will act whether it will have install and upgrade features or just install the secound tells what kind of liscences it will accept OEM will only accept OEM liscences you will have to reinstall all machines to make this happen.