What volume of data are you sending? An Xbee may not have the bandwidth you need: they max out at 115K, even under ideal circumstances.
Only slightly more expensive would be to set up a couple routers, reflashed with dd-wrt, with Yagi antennas to maximize range and avoid interference. That would give you an Ethernet link for cameras and such, plus (if you pick the right router) a TTL serial port to interface to an Arduino.
For a really solid, professional 900MHz link (though also limited to 115K), check out the MaxStream radios from Digi. I know people who've done 10-mile-plus links with them under near-ideal conditions (central node on a mountain top, in the desert).