Non-profit organizations or charities are considered by the copyright holder to be commercial entities. If you are a webmaster in the business of creating home pages or if you own a business and are promoting it on your site, you are considered commercial. Write to the owner of the graphic and send your URL to seek permission. Perhaps you will be able to buy or use the graphic. If you are making money with the image, so should the artist.
Some people try to make money with free graphics.
It's tempting to download graphics and start selling them. We all can stop this kind of business if we don't buy it. The following cd's have pirated my animations, please, DON'T buy them. Web Designer 98. So we need everyone to help just a little.