No.
A motherboard is esentially able to work thanks to these "chipsets".
Northbridge usually stands on the "north" of the motherboard. Northbridge is more important than Southbridge (which... err... stands in the south) because it controls the AGP, memory, and processor bridges. In other words, the Nortbridge determines what memory, processor and graphic interfase you can use.
Southbridge controls mostly all of the I/O in the motherboard, such as hard disk drive ports (PATA or SATA), floppy, PCI (regular one) and integrated functions, such as on board LAN, Sound, Parallel ports, PS/2 ports, USB, and Serial ports. While important, many overlook this chip in favor of the northbridge.
cheers.