If he ever authenticated it on his computer it will be difficult to transfer it to another computer. Even for a retail version I am not sure rights are transferable to another owner to install on a different computer. If it came preinstalled by a major manufacturer on his computer or is an OEM version it cannot be transfered at all under any circumstances.
I would get the key from him and call Microsoft and see wthat they say.
Whether or not you can even install XP at all depends if the hardware and bios on your computer will support XP.
Transfering XP to another computerhttp://www.michaelstevenstech.com/xpfaq.html#06
s your computer able to support Win XP
Get Step-by-Step InformationReview the "Getting Started" guide, which provides essential information on upgrading to and installing Windows XP. Remember to run antivirus software before you upgrade as described in this Knowledge Base article.
Check Your System Requirements
Make sure your computer is ready for Windows XP.
Find Out If You Qualify for an Upgrade
Check to see if your current version of Windows is eligible for an upgrade to Windows XP.
Make Sure Your Hardware and Software Are Compatible
Use the compatibility search tool or download the Upgrade Advisor to make sure your system, devices, and software will work with Windows XP, and install updates if available.
Get Step-by-Step Information
Review the "Getting Started" guide, which provides essential information on upgrading to and installing Windows XP. Remember to run antivirus software before you upgrade as described in this Knowledge Base article. http://www.microsoft.com/windowsxp/home/up...ng/default.mspx