Assuming you have an 8051 variant fast enough to handle the data rate, something like a 100Mhz SiLabs part, you might consider the new Microchip 100Mbit Ethernet chip (ENC624J600) with integrated PHY. It has both SPI and parallel ports, tho you'd likely need to use parallel to get the thruput. Run it over a dedicated point-to point link, no hub or switch, into a PC ethernet port so there's no collision latency.