++ to Microcenter. Very knowledgeable crew, but sometimes they have a very limited selection. I highly recommend browsing for reviews On Newegg
http://www.newegg.com/
You'll also be hard pressed to find a better deal on a laptop even when you factor in shipping. Newegg's return policy is also the stuff of legends.
As always, I highly recommend Acer laptops. If you're getting something with Windows XP, it's worth the extra little bit to get XP Professional rather than Home or Media Center. If you can find them in your price range, it would be a "Neet Trick(tm)" if someone out did Lenovo as far as quality of hardware goes.
If I had $500 right now, I would buy this
http://www.newegg.com/Product/Product.aspx?Item=N82E16834115482
Twice now I have purchased Acer laptops in the $500 range and twice now I have been satisfied with performance and longevity in the laptops. That particular keyboard may be a bit of getting used to. Might check with your daughter to see if it's something she might like. Maybe Microcenter has a display model she can test drive.
Edit:
Oh I see you've already heard of Lenovo. They are the manufacturing division of IBM. So basically you're buying a ThinkPad. Excellent machines. I'm using one right now actually.