Microsoft Windows x64 Edition Technology Advancement Program
The Technology Advancement Program is designed to assist customers who have acquired a new x64 Computer with the intention of replacing a previously licensed 32-bit version of Microsoft Windows XP Professional with the 64-bit version.
In order to be eligible to receive Windows XP Professional x64 Edition, your computer must have been ordered between March 31, 2003 and July 31, 2005 with Microsoft Windows XP Pro (32 Bit) preinstalled. Shipping is $12 US, or $22 US for international orders.
As always, there are “gotchas” (such as voiding support with your PC manufacturer) so be sure to read the fine print. But if you’re ready to take the 64-bit plunge, grab your COA ID or your Product ID, along with your date of purchase information for your PC, and log in.
URL: https://microsoft.productorder.com/clientx64/default.aspx