HDA = High Definition Audio, which is the latest sound standard found in most new systems.  My T42p had AC'97, my new T61 has HDA.  AC'97 works with the older version of UniAud, but HDA does not.  So you need the reuilt version of uniaud32.sys from Paul Smedley for the

HDS support.  I

believe the last release was http://download.smedley.info/uniaud32-alsa-1.0.17-20080716.zip   Keep in mind this stuff is in development.  Sound works here on my T61 using this setup, but it is somewhat flakey still.  I have system sounds off because there are hangs with playing more then one sound instance at a time.