KDL-52XBR4 or KDL-52XBR5

I was asked what I thought of the Sony KDL-52XBR4 or KDL-52XBR5. The only difference I see is that the XBR5 has a RS-232C port. What do you use the RS-232C port for ? Looks like you can connect your computer to the TV and send commands to it, to perform some functions. Also some devices these days contain RS-232 ports to connect to the TV for communicating from device to TV either for data to what is displayed on the screen or again for controls.

There is a $400 difference between the TVs just for the RS-232 port. Not sure if this is worth it. It looks like the same TV besides that feature.