How much better is the Nikon d5100 as a pose to the d3100?

I've been saving for a dslr camera for a long time now and I'd like to know which camera to go for.
I don't know whether to save a little longer and go for the d5100 or to just buy the d3100.
Is the d5100 worth the extra money? Does it have an external mic input to make good quality movies? Is the swivel screen a buggar or is it handy?

Http://snapsort.com/compare/Nikon-D5100-vs-Nikon_D3100
Nikon D5100 is better, but more expensive.
You can easily look on the Nikon website to see if it has an external mic.
I don't think the swivel screen could really be a buggar--if you don't like it, you don't have to take it out of it's normal position. I'm just it's handy.

Here is how their sensor performance compare. As you will see, the D5100 is a great bargain

How much better? Exactly $100 worth of bettererness. It doesn't matter if they are "posing" or not.

Review here the features and price for this product

An external mice has nothing to do with better quality in video.
The swivel screen is okay, but it's useless as AF in video and live view is slow and accurate. This is not like point and shoot cameras, DSLRs have a viewfinder that beats everything else.
The D5100 has one stop higher max ISO, 4 vs 3fps, a slightly bigger body and that would be it.
Here's a DSLR Buying Guide - http://www.the-dslr-photographer.com/2009/11/which-dslr-to-buy/
All DSLRs have the same quality!

Refurbished 3100
newegg.com
a very reliable store
$480
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