I'm using XBee on my Rover5 and getting a few hundred metres, from inside the house with only a 3dBi antenna.
Have a look at the video's I've posted here and on YouTube.
In the video where you can see me outside as the rover goes past, I drive out of "line of sight" and behind a pile of rubble then below the brow of a hill.
I'm using series 1 60mW XBee Pro modules, I'll be switching over to 900Mhz modules soon to stop interference with my analogue video link.
