Not if it belongs to a previous OEM installation.
Just for clarification, a Product Key is not a COA and having a Product Key
itself is not proof of ownership or legitimacy.
The Product Key is usually printed on a COA. The Product Key is required to
install or reinstall from a Windows XP Pro CD. Many people wrongly believe that
a Product Key is contained in the installation CD.
Note that the Product Key must be compatible with the installation CD, e.g.,
OEM, Retail, Volume License, etc.
See this article for clarification of what a COA is:
http://www.microsoft.com/resources/howtotell/en/coa.mspx
