I am flemish, so dutch is my first language.
Since TV shows and movies are never overdubbed here, but always subtitled,
most dutch-speaking people also speak relatively fluent english.
However, they have a (sometimes annoying) tendency
to start conversating in english with foreigners if their dutch is not thàt good.
You'll always have to stand your ground and make it clear you wànt to speak dutch.
It's easier to learn native languages in countries were most people only know a single language.
But if you DO learn dutch, you will get a lot of respect from everybody...
I'm American, but have lived and worked in both Flanders and Holland. I speak Dutch. Dickturnip is absolutely right. Many Dutch-speakers will switch to English, which makes it hard to practice. Take a good course of Dutch for a year (there are some in every urban area - ask your colleagues or other expats for recommendations), and be absolutely hard-nosed about speaking in the Dutch you know to practice, even if native speakers switch to English (or even complain about your lack of speaking fluency!). You will be able to pass the Staatsexamen, and when you speak Dutch well the native speakers will give you additional respect.