I bought my D80 with the kit lens which was the 18-135 and I also got the 70-300VR. I still have them. I used the kit lens until I bought the 18-200VR. The 70-300VR came in handy many times for longer reach. It's a very decent entry level zoom lens.
I also didn't know about lenses when I bought my D80, and was still (am still?) trying to figure out my style.

I invested in the 50mm 1.8 (wish I had gotten the 1.4 which was much cheaper than it is now). The 1.8 is still a very good lens for the price. It has nice bokeh...but I know the 1.4 lens is even nicer!

I also got the 85mm 1.8 (again, wish I had gotten the 1.4 but it was and is still priced out of my league). It's a really nice portrait lens though; it's just, I know the 1.4 would be even better!

(Okay I am addicted!) I got the Sigma 10-20 which is good enough for wide angle shots, and the Sigma 30mm 1.4 (I love this lens!). I also bought the Sigma 18-50 2.8 which is also a nice lens, but with the rest of my arsenal, not used as often as it could be primarily due to size and reach. It's just so much more convenient to not have to swap lenses unless I know I'm taking a particular type of photo that would require the use of a different lens.
Since I got the 18-200VR, it resides on my camera 90% of the time. It's a great walk around lens. I know it's not very popular on some of the other pro camera forums, but for what it is to me (a total amateur) it's great! If you can get the D90 w/ the kit lens which is like 18-100 or something like that (see Wenrob's post) I heard that it's supposedly an even better lens than the 18-200VR as far as optics go. That's what I've read anyway in some other photography forums. Of course, you'd be missing some of the reach... I seriously would try to swing the 18-200VR if you can. It does come in handy and you won't have to worry about swapping lenses when walking around the parks or anywhere else. Don't get me wrong, I still use my other lenses, but if I'm just looking to grab the camera and go without lugging around the entire bag of lenses, the 18-200VR is what I take. It's very convenient.
I can't bring myself to part with any of my lenses even the original D80 kit lens!

I keep the original kit lens just in case something happens to my 18-200VR. My DH was relieved that when I bought my D90 I got just the body and no other lenses.

My dream is to be able to afford the 2.8 Nikon lenses...maybe one day...Welcome to the land of NAS!
Oh yeah, I'd really weigh the pros and cons of the D5000. I heard that Nikon has issued recalls on a bunch of them, something to do with the battery IIRC. If you can swing the D90, it's a great camera!