Hi Rick,
I've spent quite of bit of time looking for alternatives to MathCad. I've been using it since the beginning and am a big fan, however, it's hard to be enthusiastic about the future. I talked recently with one of the marketing folks and he assured me that Prime 4 would fix many of the complaints about Prime 3.1. I really want him to be right, but I'll wait and see.
Basically, there seem to be four big choices: Matlab, Mathematica, Maple and Mathcad. There are, of course, some others, but it's tough to make a big time investment in a code that might go away without notice. In terms of user base, it appears to me that there is basically Matlab and then everyone else. The Matlab user base is huge and appears to be spread over much of the World. The user interface seems clunky to me; otherwise it's pretty good. Mathematica and Maple certainly have a significant user base, but Matlab is the program I see everywhere in the engineering world.
Being a Mathcad user is beginning to feel like being one of the last speakers of a dying language. This semester, my students voted unanimously (undergrads: 80-0, grads: 19-0) to use Matlab for all calculations in class. They are very convinced that Matlab is a marketable skill. I had to confess that, while I really like Mathcad, they'd probably never see it again after they left school.
I had originally planned to go to Maple for my classes, but my students were pretty clear about what skill they thought they needed. Fair enough.