When Web material duplicates rather than complements the lecture or textbook, some students will not choose both sets of resources. I like them. It's easier to ask a question via e-mail than in class. In one class, we left the building to find a computer so that we could discuss the course work with each other. So I had to ask other students about it.
File size is an additional factor, especially if students are using a modem.
Faculty are encouraged to orient students to using the Web at the beginning of their courses. We are located at 1301 and 1307 University Avenue, Madison, Wisconsin.