I bought a Lenovo IdeaPad Y510 for $529 after rebate earlier this year.
It has:
15.4" Widescreen
250GB hard drive
2GB RAM
DVD Burner
Pentium Dual Core Pentium @ 1.6 GHz (think Core 2 Duo @ 1.6 with half the cache)
Intel chipset and embedded video
2.5 hour battery life with normal, real-world use
Great Lenovo keyboard
Drivers for XP are downloadable, but it comes with Vista home premuim.
I don't game on it, but I do professional writing, note taking, software testing, and software development on it, and it is plenty fast for this. In fact, it benchmarks 30% faster than my 4 year old Pentium 4 @ 3GHz.
On top of this, it is extremely well built - no cheap plastic, no flexing, no creaking. The only problem is the screen is too close to the keyboard when the unit is closed, but a piece of lint-free cloth placed over the keyboard before closing it takes care of that problem (most Mac users are familiar with this problem too.)
I've bought Vostro Notebooks from Dell for a few clients this year too. They are perfectly fine, and can still be had with XP for a small additional charge. I must tell you that I think the IdeaPad is a more pleasant notebook to use, but the Vostros I'm responsible for have been holding up well and are priced very well.
Hope this helps,
Llama