For search rankings text links are more valuable than image links because the anchor text used to link to each page helps raise each page’s ranking for those keywords. If you do use images to interlink your pages, then please put the keywords for the page in the alt attribute of the image tag. If you take a look at the HTML for my dinosaur website: http://www.mantyweb.com/dinosaur
You will notice that each of the image links has alt text that uses appropriate keywords to describe the page. For example:
The example above is the image link “Home†on my dinosaur website. The text highlighted in red is the alt text for this image. It says “dinosaurs for kidsâ€, which is the keyword phrase that people use to find our website in the Search Engines. Use this technique to tell the Search Engines what the page is about.
Text links are preferable, so if you use image links in your main menu it is a good idea to include text links at the bottom of your pages (like on http://websitepromotionbook.com).