I THINK that is a 566.0074 with a 684 movement. The 684 is an awesome movement! It is a scaled down version of the 55x movements, scaled down for use in ladies watches! 24 jewel, higher-beat + date, the only nicer IMO of the ladies movements are the 685, which adds chronometer certification.
As far as the watch: its lovely, and seems to be in reasonably good shape from the pictures you took. There isn't much for sales history on this one, as it just isn't traded very much. The only sale recently on Ebay was for $100, but it was non functional.
This watch has an additional 'difficulty' however, in that the front crystal gasket is quite unique, and thus very difficult to find (though Omega/A certified Omega Watch Maker (with parts account) MIGHT be able to get one).
Given its size (that is a 27mm case), that it is a ladies watch, and its style, I'd put the value ~$350-$500. Ladies Omega watches tend to stay about the higher end of that, but this is an awkward in-between with a style that doesn't seem particularly popular for ladies, so I don't see it being anywhere near the top end of that.
