And as an alumnus, I’d highly recommend the University of Washington’s Technical Communication program as a great way to transition from “pure” TC into usability or design.
As a designer who started out as a technical writer, I enjoyed reading Theresa Putkey’s article on Using Technical Communication Skills in User Experience . Whenever people ask me how or why I got into design with an English degree, now I can point them here instead of re-tracing my own circuitous route to design nirvana. (My own career history also included a very satisfying 5 year stint as a usability engineer, but the general career path and motivations are the same as outlined here by Theresa.) A good read for anybody whose job is essentially “explaining why it doesn’t work right”—and is tired of it.