[ubuntu-uk] [OT] - MS XP Pro OEM CD - How?

[Eddie Armstrong]

Sorry to ask MS stuff here but I have been trying for days to find an 
answer to this and hope some of you may be able to help.
I have been given two old PCs with MS XP Pro SP2 installed and licence 
OEM sticker on the sides and would like to re-install clean XP Pro and 
dual boot Ubuntu.
 From what I have been able to decode from MS licence agreement by 
upgrading  these machines I am legally entitled to OEM status.  Is this 
true?
I also understand that any OEM XP Pro SP2 disc will do?
However I have no OEM disc , Amazon sell a new one for £84 but I already 
have licences that go with the machines.
Does anybody know where I can obtain a OEM disc, cheap?
Obviously I want this to be legal so users of the PC can use  XP or 
Ubuntu legally.
Any help appreciated.
Eddie