Changing the motherboard is like building a whole new system. You don't have to re-install the OS. It is recommended, but if you uninstall the old drivers and install the new ones it will migrate fine. But from a hardware perspective, it is a pain.
You also really don't want to from a financial standpoint. Think about it. You pay $60 for a motherboard. Later you buy one that is $120. Great. So you rebuild your PC, and have a computer with a better motherboard and a $60 paperweight. You could always use it to build another system, but obviously that will have added costs. You might be able to sell it, but low-end motherboards don't usually sell well after they are used. It just makes a lot more sense to just buy a motherboard and stick...