From the perspective of a student who's honestly just trying to get his money's worth out of four years of undergrad, I appreciate the perspective and honesty of Rachel and others on the research vs. teaching issue. The knee jerk part of me is bound to immediately advocate teaching as the essential over research at all costs: I fear the professors who are too obsessed with the sub-concentrations of their fields to have the breadth to teach intro courses and are willing to help us lowly freshmen.
I come from a self-labeled "medium sized research university," and much of what goes on, especially in my department (political science) is to a certain degree specialized. However, I think that a balance must be struck between these two extremes to keep professors personable while keeping them engaged in their fields. The worst professor I've ever had is the one who placed the entire burden of teaching on his TA. In his case, that meant showing up late for classes when a quiz was administered, regularly being absent from lecture, playing irrelevant videos in place of lecture, etc. This prof assigned six multiple choice quizzes and one final - no papers, no discussion - while other sections of the same introductory class taught by different profs went far more in depth. I came to the obvious conclusion that this prof cared naught about his undergraduates and spent most of his time on his "research" (which was more like feeding quotes to newspapers than it was actual academic study.)
The best professor I've ever had actually had a heavy research load - he was brought to the university to head a center for his area and has written extensively on it. The way he went about applying his background, however, produced a number of advantages. First, he assigned his own book only as an optional text (bad prof had us read the whole thing and it was terrible.) Second, his experience in the research field lead him to choose primary and recommended texts that he not only knew extensively, but knew their authors as well. (While clearly, not every prof has this luxury, I was very happy the professor didn't saddle the class with a $50 - 100 text he didn't care about.) Third, he made the assignments for the course research-extensive, allowed us to travel down the same paths he once did, and offered extensive commentary on research essays not only about my writing but about the balance in my source citations, points I may have missed, etc.
I came away from the course not only with much greater knowledge about the subject than I could get from reading a book, but also having learned a very important skill. It is not coincidental, I don't think, that this professor's favorite rant was about the Ivory Tower nature of academia. As long as a professor remembers that his or her students are people, many of them are eager to take the course and at least some actually want to learn, then research does not have to be a vice.