I was in a similar position about a year ago, with a twist: I had to have two bodies for a shoot, circumstances dictated I couldn't swap lenses (outdoors, -20F, etc). I needed some glass, and I needed bodies that were a little "sturdier" than the D5000.
I played with the 7000, and decided that the control layout, etc., was so different that I couldn't, in the heat of the moment, use both bodies effectively. So I purchased 2 D7000 bodies. By "heat of the moment" I mean that this was a sporting event: dogsled race and weightpull, and skijoorning. No way am I good enough to switch from the 5000 controls to the 7000 and not flub the action shots.
Then later I worked on building up my glass. Still working on that, NAS blows.
With that said: a lot depends on what you're shooting, IMO. If you're shooting in relatively controlled conditions, the 5000 produces excellent images. Yeah, it won't have the high ISO performance, nor the dynamic range, of the 7000, and the controls are not nearly as flexible, not as high a pixel count, yada yada. But I've shot many images with the 5000 that I still am proud to print and show.
But as much as I liked the 5000, the 7000 is a major upgrade in every way. A year later, I'm still thrilled with the 7000, and am still practicing and learning how to make better images. It's really a great introduction, IMO, to a professional level DSLR.
The other comment I'll make: the 17-55 is a dx lens, albeit a very good one. However, I made a decision to avoid investing in DX lenses, just in case I make the switch to FX format down the road, I won't have to lose as much money. Something to consider.