Yes, the barton is the better chip.
Are you interested in OCing at all? Of the people who have tried OCing the xp2500, 92% have been able to run them @ 3200 speeds. When you consider that some of them had boards that only support 333 fsb, and people who were trying for the first time, that is an impresive number.
Try reading a little in the OCers forum, before you try or buy. If you have any questions, please ask.