The Microsoft Clip Art Gallery provides a compilation of artwork for your personal use. Microsoft licenses some of the artwork from third parties and therefore cannot grant permission for you to redistribute the artwork. For more information on the terms of use, refer to the End User License Agreement (EULA) that accompanied the product from which you obtained the clip art. If you obtained the artwork from Office Online, you can find the EULA at http://office.microsoft.com/en-us/FX100667421033.aspx.
Many other product EULAs are available at http://www.microsoft.com/legal/useterms/.
The following guidelines apply to the use of clip art:
1. You may use clip art in your school assignments and projects.
2. You may use clip art in your church brochure.
3. You may use clip art for personal, noncommercial uses.
4. You may not use clip art to advertise your business.
5. You may not use clip art to create a company logo.
6. You may not use clip art to illustrate the chapters of a book.
More info here: http://www.microsoft.com/about/legal/permissions/default.mspx