this should do it !
http://pcsupport.about.com/od/produc...hangexpkey.htm

I have already tried that and it did not work. The error response was something like this, "Wrong key or maybe mistyped". I do know that I did not mistype it. I know there is a difference between OEM keys and Retail (volume license) keys. I think that because I installed a retail version, I have to use a retail key and that means that I can only replace that key using the above method with another retail key. I am still unable to change out the key with the OEM key on the computer. Thanks for the advice, though.

Here's the Microsoft Product Key Update Tool

Will this allow me to change it from Retail to OEM?

idon't understand what changes you expect ,i use a retail copy of xp to reload computers that were oem machines, all the time !
are you expecting it to change something besides the windows key!,i have never used the windows key changer program ,i have only ever used the method in my other post !