Also think about your relationship with your manager. Would he or she have reason to think that you'll waste your last two weeks or distract your co_workers instead of doing what you can to make the transition seamless? If so, you may be asked to cut your two weeks short.
Prepare for It. This one is easy. All you have to do is smile and say "Thank you so much for your support. I've enjoyed my time here and I've learned a lot from you. Let me know what I can do to make the transition easier." Are you always going to get reaction number five? Probably not. But if you look for the signs, you can likely anticipate your boss' response, go into the conversation prepared, and come out stronger on the other side. Then, you can breathe a sign of relief and start looking forward to starting your new position.