PRINT - The files labeled PRINT are saved as EPS. Internet Explorer for Windows has an idiosyncrasy that causes it to try to save EPS files with a .ps file extension. If you use Internet Explorer for Windows, right click on the file you need, choose "Save Target As...", and make sure the file extension in the Save As dialog window is .eps. For instance, the wordmark file should be "wordmark.eps" not "wordmark.ps".
Use the files labeled PRINT if you are going to have something printed. They will look good no matter what size you use them. You must have a PostScript printer to print them. You can also use them with PhotoShop to produce custom-sized web graphics.
WEB - The WEB files are saved as GIFs. Please do not use JPEGs or GIFs for printed material.