xHTML is the language which is understood by all browsers, that is why it is mostly accepted to view the contents of the website. It is simply a combination of HTML and XML so as to overcome the compatibility issues. PSD to xHTML coded designs will enhance the look of the website as its code is easy to embed and write. When it comes to SEO value, such websites are very SEO friendly and give excellent results. So try to focus on hand-coded designs only which are superior in quality.