Great place to visit
2 places you can't miss are Anne Frank's House and Madame Tussaud's Museum. But you have dozens of museums to visit in Amsterdam, so you might want to plan your trip carefully.
As for Red Light District... get ready to find dealers wanting to sell you cocaine, trannies who are hotter than many playboy girls (yes, I found it hard to believe too) and make sure you DO NOT take pictures of the girls standing in the "windows", unless you want to get beat the shit out by the pimps =P
Have fun.