Interview... the internal kind

[Fast Food Knight]

So, I'm up for a possible promotion at work and I have an interview tomorrow. I'm looking for suggestions/experiences from internal interviews (vs external). I've done a million external and feel really confident about them. Are there any differences between the two? Anything I should definitely do or not do? Have you any of you even been the interviewer in a situation like this? I have it at 2pm tomorrow. Any tips or experiences would be awesome. FWIW I work for a large corporation, but am familiar with the people that will be interviewing me.

Thanks guys... wish me luck!