I'd also look at the Acers they sell at NewEgg.com If you visit the Acer site you'll see they have tons of combinations of features, screens, and OSs, so I'd see what I like out of their options and then go look at what NewEgg is charging. You can price in an extended warranty any number of ways, and then compare it with Dell. Putting the external equipment on is a great way to make it work more like a regular computer, but if you look at the prices of regular desktops, they've come way down. Will you ever want to bump this up to a regular computer, or are you looking for a net device for it's mobility?
I played that "what if" shopping game recently for a friend. By the time you add the software you want and get the operating system you want, they can come out about the same price, if you already have the monitor, keyboard, etc.