While it's a really good idea to make sure your library's website is
prominent on your institution's page (because I think that does send a
strong signal, even to students, that your library is important to your
campus), the really big question is how easily your students will be able
to find your web page by googleing "University X Library", or "University X
JSTOR" or "University X Ebsco."
When a student has an assignment and their professor tells them they have
to use "the library", they'll probably Google you - they won't try to
navigate links from the university web page. I agree with Cary that your
*current* students/users will probably not be going that route. So ensuring
your page and its content is easily Google-able and search-engine optimized
(and not hidden behind a portal!) is key.
Systems & Emerging Technologies Librarian, CSUN
Systems Coordinator, PALNI