You should properly setip your pages, so they can be called similar in fashion to index.php?page=page_name. It means that you need to be able to type index.php?page=page_name at the address bar, then the index.php file delivers the whole page. The script for the index.php should also be altered, if the GET variable is configured at ajax_caller=true set. The you will be able to a unique content to the page, such as index.php?page=page_name&ajax_caller=true. The Ajax caller function needs to be configured, so it will properly accept the page parameter and you are able to call the proper URL. Each of the links should be set up, so the HREF attributes are set to the onClick attribute and to index.php?page=page_name. These are essential to ensure that your Ajax implementations will work well in any SEO project scenario.
By configuring things similar to the above, you can make sure that search engines are able to follow links. You will have identical view as users who gets the Ajax enabled and you will be able to deal with more advanced interfaces. However, you should be aware of the Ajax methodologies that can result in a number of side effects. As an example, users can be allowed to bookmark specific pages, because you have given them the link. Many browsers allow you to bookmark the link by right-clicking it. The friendliness of your search engine should be maintained. You should know how to perform various functions, such as controlling the Title and Meta tags of the page content.