David, I'm moving your post out of the "off topic" folder where you posted to.
The previous answer referred you to support, but if you are having a problem entering credit card information, make sure that there is no punctuation in any of the form fields such as commas and dashes and apostrophes.
If you are being told that your LiveID is incorrect, open OneCare, click on Help/About to see the LiveID called the Subscription ID. Use that to log in at http://billing.microsoft.com to renew.
-steve