Didn't know about this feature till I read this article - http://builder.com.com/5100-6371_14-5061538.html

You can also use Dreamweaver MX to convert existing HTML files to XHTML 1.0 Transitional. After opening an HTML file in Dreamweaver, select File | Convert | XHTML. If Dreamweaver encounters code it can't convert, such as <img> tags without alt text, it provides a report at the end of the conversion process. From there, you can manually repair the offending code.