Hi,
If your aim is to build a display board which can be control by Computer, then what i recommend is ..just a microcontroller will do a good job for you. Using FPGA for this will be over killing. Again Programming microcontroller for RS232 or any other interface available in PC (like USB) is easy as compared to writing code for this in FPGA. Well, more over most of the microcontroller are now available with UART, USB, ethernet interfaces and the one which is the most important for your task is..display controller may LCD or 7 segment display.......So checkout this option...and go with microcontroller based solution.
Best of luck........