Joystick connected to PC connected to CAT 5 to Arduino

Hi, all I am new with Arduino, and am trying to think things through step by step. My project is to create an ROV with 3-4 motors, controlled by a laptop on the surface via a CAT5 cable/power umbilical. I need to learn a lot of things, but the first thing I would like to figure out is how to send joystick commands through the PC to the Arduino. My first step will be to send data from the PC and joystick to the Arduino to light up LEDs that mimic the motor outputs. After that, there will be a lot of tweaking, adding sensors, but it's downhill. So, is it possible? If so, where do I need to start? Thank you in advance.