I bought a no name pc with a fully validated and activated XP Pro system. The seller would not include the OS disk but the price was good so I bought it anyway. The pc has an OEM XP Pro (no sp) sticker on it but when I check the EULA it shows WX.4_PRO_RTL_EN. That is, as I understand, the retail version, and I know the previous owner did replace the hard drive. I was thinking of ordering an OEM from Microsoft, but my concern is it may not activate. I have no way of knowing if the hardware in this pc will match the OEM installation or if it even has to match. Does anyone have any insight into no name pcs?