>>5 has a valid point.

You have to gauge your relationship before you can accurately go ahead and ask her out. If you're childhood friends and know each other very well, then maybe just spending time together (even for a meal) really isn't anything too special or out of the ordinary. You'd probably have to give a hint of your intentions. Or plan something that you wouldn't normally do (like see a musical or play). But if you two aren't extremely close, then maybe going out to dinner and movie is special enough. Maybe telling her explicitly that "I like you" is a bad idea, however, as long as she understands why you're taking her out, it shouldn't be a problem.