When you want to play with the arduino chip you might consider some usefull toy. The tank rover from Robotshop will give you a platform to play with. With the complete set you get:

• pcb with ATmega328 chip
• frame for holding tank tracks
• battery holder
• Tamiya gearbox and tank tracks
• 2 XBee modules
• 1 usb adapter for the XBee module
• 1 XBee shield to put on top of the rover
• Solarcharger shield to put on top of the rover
• LIPO battery

The basic assembly of the gearbox and tracks is pretty simpel but does require some attention. Dont forget to look at the manual if your still following the right way os assembling it

Altough there is no supplied manual and the manual online is very limited you should be able to assemble the tracks, the frame on the pcb and the gearbox. All put together you should be able to test basic functions of the rover. Download the arduino development software and connect the rover using USB. When asked for an driver look in a subdirectory of arduino software for the driver. By default its programmed to send out the values of the temp and light sensor on board. The 6 bright blue lights make it look very nice in the dark, only pitty it cannot be controlled from the program but only manual by a jumper on board.

Second step should be add the solarshield and XBee shield. First install the XBee on the XBee shield and the second XBee on the USB adapter. Make sure you set the jumpers on the XBee shield to XBee instead of USB else the XBee will not recieve the text from the chip but the USB port would be. By default the XBee modules are set for transparent mode at 9600 baud so it should work right away.