your client nic needs to know where to look, your server nic needs to sport tftpboot and dhcp (optionally, but sometimes required if client can't define IP, etc)
Mac's, and Sun's can define IP info prior to boot, but most x86 roms are kinda minimal
so to make up for that, ROM-o-Matic can be used.
if you need to resort to a dhcp server for client (so you dont need the rom-o-matic), youll need to define many things, MAC, kernel, IP, et al
i should clarify, dhcp server, on server, not client machine