To obtain one go to http://www.microsoft.com/windowsxp/m...p/default.mspx
And fill in your details.
You also have to answer 4 questions correctly to win one.
The answers are:
Q1. How many ways are there to obtain a full Microsoft® Windows® Desktop license?
Q2: Volume License Agreements cover Windows Desktop operating system upgrades only.
Q3: OEM operating system licenses are non-transferable.
Q4: The most cost-effective way to acquire an initial, full underlying Windows Desktop license is preinstalled.