If you can't install the clip gallery tool on your computer with Windows 7, you can try to add the clip art items on your own. To do that, copy your clip arts to the following location in your computer after you installed the Publishing application :
C:\ Program Files\ Microsoft Office\ Clipart and
C:\ Program Files\ Common Files\ Microsoft Shared Clipart. By doing this, the copied files should be available to use in Microsoft Publishing program.