Hi,
Difficult to compare the two.
Ours is Centrino 2, DDR3, larger battery, longer warranty - to name but a few
Whilst we sell many Dells the one I think you're referring to is "End of Life" and whilst its a bargain today you're buying a previous model that limits any upgrade potential.
We'll have some £500/£600 solutions with next gen gear that'll compete nicely with the XPS...but at the end of the day you pay for what you get and I am confident our prices will be very competitive.
Afterall I want you guys to buy them