Hi,
We recently had the requirement to show the SharePoint ribbon to only the Admin user.
The best possible way of implementing this using SharePoint Security Trimmed Control.
We need to wrap the div with id ms-designer-ribbon inside that control.
http://blog.crsw.com/2007/11/05/spsecuritytrimmedcontrol-conditionally-display-contents-by-security/
Hope it helps ..