There are two different problems in your post. If you don't know the LiveID for your subscription, then you can't possibly sign into the Billing site to provide the credit card information. If you can sign into the Billing site - http://billing.microsoft.com then you are part way there.
The credit card form issue is due to an incorrect country/language setting for your location in IE.
Open IE and in Tools/Internet Options, verify that your language setting is correct for your country.
If it is not, click "Add" to select your language and country combination from the list.
Make that selection the default. It should appear at the top of the list.
Remove or demote other entries that are not appropriate for your country.
If you don't recall the LiveID you used for your subscription, you will need to contact support who can provide that information to you using your Key and/or contact information.
How to reach support (FAQ) - http://forums.microsoft.com/WindowsOneCare/ShowPost.aspx?PostID=2421771&SiteID=2
-steve
