It does'nt matter, when you are using the connection only for internet, you dont need to boot from LAN. You can disable it, but you can choose by yourself.
All of these responses are incorrect - it does not have to do with network booting or Wake-on-LAN.
LAN BootROM has to do with providing gigabit functionality on older operating systems that don't have proper diver support, such as MS-DOS. If your operating system was made after 1999, you should probably leave it disabled, as that will allow your machine to boot faster.