A week is not a plateau. Keep going for another 2 weeks or so. Most likely the scale will move a bit again. If not, you have a lot of options. You can up or change your exercise (adding HIIT, for example, or adding more minutes to your exercise), lower or change the source of your calories (lower by 100-200 per day, or shift more calories to protein sources instead of carb sources).
But really - a week is totally normal. The scale fluctuates. There's a great thread with reasons for this:
http://www.3fatchicks.com/forum/weig...er-weight.html
A week is not a plateau and is totally normal.