Hi Steve - thanks! With a little modification I got it to work. This is what I did:
1 - quit Aperture
2 - deleted my online store account completely
3 - Check that you are using the latest version of Aperture. You can find out more information on updating your software here:
Mac OS X: Updating your software
http://support.apple.com/kb/HT1338
4. Reset your keychain. Follow these steps to reset your keychain:
a. From the Finder menu, choose Go > Utilities to access your Utilities folder (or press Shift-Command-U).
b. In your Utilities folder, launch the Keychain Access application.
c. Find the "NetServices" entry in your Keychain Access window.
d. Select the "NetServices" entry and press the delete key.
5. Relaunch Aperture and attempt to place your order again.
6. You should be prompted to enter your account information if you deleted the keychain entry successfully.
7. After entering your account information, you should be able to complete your order.
I had some steps from Apple support and with what you gave me this seems to have solved the problem. Cheers
Mike