yes, you need to match the Motherboard socket to a CPU with the right amount of pins, eg. socket 462 CPU goes with a socket 462 motherboard.
by the way, your motherboard socket is 462, not 478. so do not get that CPU because it will not fit. you will need something like an "Athlon XP 3200+ if you want to upgrade. but you will probably need to update your motherboard for that cpu, even though it is socket 462, because it is likely an old board.