I agree with the Vostro 1500 (15.4"). It is an awesome deal. I had the 14.1", but had to return it because I couldn't sell my old laptop. They had a 30 day free return policy when I bought mine. They do offer them with XP if you prefer that and you can easily get one for around $800 with the specs you are looking for.I'd definitely go with a Dell. I still have a slightly older e1505, and it's fantastic. The screen is amazing...I'm not sure if they still use the same LCD manufacturer for the newer Vostro models. In all honestly, you can get a brand new 15.4" Vostro that meets your qualifications for <$700 pretty frequently.
If you want a 17" screen...probably be prepared to fork out the cash. Although there are some deals for some other brands' 17" models from time to time, they are generally quite a bit more expensive. And pretty hefty to deal with on a regular basis.
Some advice, if you upgrade your ram then do it yourself and save like $50.