That web-site _does_ work for me.
It redirects to:
This latter page states:
Welcome to the Windows 7 Upgrade Option Program from HP
This program offers a Windows 7 Upgrade Kit for qualified HP PC customers.
For the easiest ordering process and to avoid delays we recommend that you:
1. Place your order using the eligible HP PC (or have it close-by)
2. Scan a copy of your eligible PC proof of purchase before you begin ordering
1. Proof of Purchase (receipt, packing slip) is required to complete your order.
2. Shipping and handling costs may apply. Your credit card will not be charged until your order is shipped.
The Windows 7 Upgrade Option Program from HP requires you to provide your HP PC product serial number.
Your serial number will be used to confirm program eligibility, and, after program completion,
will be archived by HP to meet Microsoft program requirements.
* I agree to provide the serial number of my HP PC in order to place a Windows 7 upgrade kit order.
Their "Contact Us" page states:
Important Customer Message: We are currently experiencing very high call volumes due to customer excitement over Windows 7. Thank you for your patience!
Please check out our Frequently Asked Questions for the answers to many common inquiries. If you have an existing order, please click on View/Track Order for current order status. Customers with accepted orders will be receiving an email in the next few days with updates on shipment schedules.
Phone (U.S. and Canada): 1-877-280-2279
*Support available Monday through Friday 10AM-10PM and Saturday 12PM-4:30PM (Eastern time)
If you're on dial-up, scan the original receipt,
and find the "serial-number" somewhere on the case of your computer.
Then, find a computer (Public Library? Internet Cafe' ?) that has a high-speed connection, and try again to access the web-page that they told you to access.