Not my first choice but...

Let's say that you're interviewing for a position that's really not your first choice and not an area that especially interests you, but you need a job so you take what's available.

What's the best way to present yourself at the interview? Do you suddenly do a 180 and pretend that you have always had an overwhelming burning desire to work in that area? You don't want to admit that it's not your first choice, because who wants to hire someone that's less than enthusiastic, but I'm not comfortable with lying either.
If I need the job I would lie. Sorry, but the competition can be fierce and you got to do what you got to do.On the other hand, I will bust my butt trying to do a good job for them whether it was my preference or not.I think that is a fair deal.