In the Software Update search folders SCCM 2007 always shows updates which aren't required by any host in your environment.
Here's a quick howto so only required updates with a minimum of 1 are showed in the search folders.
Select the required search folder and choose Modify Search Folder criteria.
Choose the Required option and add the following values in the Search Text dialog
The number specifies 'starting with' so 1 is 1 11 111 and so on.
After applying very update which is required by > 0 host will be displayed in the search folder.