The two most important things to look for in a motherboard are its speed and the quality of the chipset, a group of chips that control the board. MB stands for main board or motherboard. BX440 is the chipset model number made by Intel, who is generally accepted as the best chipset manufacturer, and this chipset is the best choice in the Intel family of chipsets. Motherboards come in either an AT or ATX form factor. In shopping for the best overall system performance, consider the speed that data travels over a motherboard to be just as important as CPU speed.
Data travels as electrical pulses on a motherboard over wires embedded in the board.
These groups of wires are called buses and there are several buses on the board similar to different kinds of highways. Some highways, like the interstate system are faster than others like city streets. The fastest bus on the motherboard, called the system bus or clock bus , is the one connecting the CPU to memory. The system bus and AGP bus are about twice as fast as the PCI bus, and the PCI bus is about 8 times as fast as the older, mostly-outdated ISA bus. You won't see any ISA advertised.