Well, corruptions fixed! If I were you, click "Check for Updates" again, to force a re-fresh. If SP1 still doesn't appear, install all other updates, and keep doing this until SP1 does appear, or you are told twice in a row that no more updates are available, and then check for the presence of SP1. To do so:
Press and hold your Windows Key, and press 'R'. Type winver
and press enter. Use the Snipping Tool to take a screenshot: How to Use the Snipping Tool in Vista - Vista Forums
and upload it here: Screenshots and Files - Upload and Post in Seven Forums
Thanks a lot!