the Xbee shield
An XBee shield. There are several to choose from - none are ideal. Some are less pathetic than others. I like the Sparkfun model myself.
TX RX both the same
If you mean can an XBee transmit and receive, the answer is yes.
and XBee interface with the PC right ?
Depends on what you mean by "interface with". I have yet to see a PC with an XBee socket. So, you need something to connect the XBee to the PC. Typically, that is a USB Explorer. That makes the device appear as a serial port. The PC can't tell the difference between an XBee on a USB Explorer and an Arduino on a USB cable. Both are just serial devices on a virtual COM port.