i take it your 'remote' pics will be operating under RS485 or so fourth (effectively and addressed RS232). the only thing i can think to suggest is ditch the 16F877 for the master and look for a pic with 2 hardware USART ( i think they exist) and use hserout/ hserin and hserout2/ hserin2 for two hardware comms.

or use the 16f877 but using hserout/ hserin for your RS485 comms(hardware USART to ensure the timing and speed is there for the network), and serin/ serout for the RS232(bog standard non hardware controlled communications ideal for the PC comms where missing an address because of the program being in a different location may not end the world.. but will eventually catch up) remembering to use the correct driver chips for the line loading etc.

Chris