A word of caution: they are not always good about posting the correct platform information about the airport bound trains from Centraal. The problem seems to arise when there are schedule disruptions on other lines and the airport train is diverted. That won't matter coming from the airport, but for the return take extra precaution that you are waiting in the right place, if possible. (That may not be easy because the workers may not care to help you at all, especially if you are American and they are Walloons.)