A separate tab in your browser or a separate worksheet in excel?
<cfcontent....> does not have the ability to do multiple tabs in an Excel output.
If you want that level of control you will either need to go to CF9's new excel integration technology.
For older ColdFusion servers, dive into the Java underling and use the POI integration technology.
Personally, I prefer the POI approach mentioned above. But a third possibility is to use Office's mso schemas/xml