Just scroll down the list of previous messages and you will find what you are looking for.
I read that Ancestry.com is free till the 6th of Sept (not a 2 week trial sign up and don't know for sure it is true) and there is are Vietnam databases there. Vietnam War, Awards and Decorations of Honor, 1965-1972 Vietnam War, Casualties Returned Alive, 1962-1979 Vietnam War: U.S. Military Casualties, 1956-1998
There is also the Veteran Affairs Gravesite Locator if any are buried in a National Cemetery, will give name, service branch, rate or rank and a notation is served in Vietnam or any other war. http://gravelocator.cem.va.gov/j2ee/servlet/NGL_v1http://gravelocator.cem.va.gov/j2ee/servlet/NGL_v1