I have S&T 2006 and have never used it, yet. Although, Mappoint has a programming interface to it, where streets your are pretty much stuck with what you get. The Streets & Trips that i have has voice prompted navigation. I dont think mappoint 2004 did. 2006 might i havn't looked into it that much.
As soon as i get off my lazzy *** and put my carpc back in i will try S&T. got mine from woot.com 40 bucks with USB GPS. Couldn't pass it up.