Adobe LiveCycle Forms is a server product that can render an XDP file created in LiveCycle Designer as an HTML form. It renders each page as a separate HTML form and provides back-end functionality to help you treat it all as a unit. LiveCycle Forms is enterprise-class server software, and it requires a big budget. If all you want to do is transform some XDPs to HTML forms at design time, then it's not the way to go.
Adobe Form Designer 5 had a "test presentment" function that could render the form designs as HTML4, AHTML, CSS2, Java applets, and WML. Adobe took that out in version 6 to focus on PDF forms.
Jared Langdon
http://www.jlangdon.ca