I mounted an xBee 802.15.4 in a breakout board
Which XBee? Which breakout board?
and connect RX and TX with TX and RX from the arduino duemilanove.
Power? Ground?
I plugged the xStick 802.15.4 in the laptop
The what?
I try Remote Configration but it detects nothing, no one node.
You tried to remote re-configure an XBee that you had never configured? No surprise that that didn't work.