The Xbee series 2 radios are not the best choice for point to point communication. The series 1 radios are better for that. Unless you already have them, in which case I wish you luck.
The simplest setup would be to have one Arduino with a XBee shield and XBee connected to the PC, using the serial/USB cable. The other Arduino with XBee shield with XBee gets the accelerometer. It reads data from the accelerometer, and sends it to the serial port, which the XBee reads and broadcasts.
The receiving XBee gets the over-the-air transmission, and puts the data on the TX/RX pins, which both the Arduino and the PC see as serial data. On the receiving end, the Arduino really isn't doing anything. One of these SparkFun XBee Explorer USB - WRL-11812 - SparkFun Electronics could be used, instead.
You don't really need the Ethernet shield, at all.
You can use the series 2 XBees, and the Ethernet shield, and 2 Arduinos, but the setup will be more complicated and expensive than is really required.