It's not going to do any harm without the chipset drivers there if you're just using the machine for basic tasks. To dumb the definition down a lot, the chipset drivers basically specify what the components in your motherboard can do and how they talk to each other and the OS. XP will have a basic driver that will generally work fine, but if you're doing intensive work (i.e. data's flying around left right and centre on your board) then you'll probably notice it operating slower than it could. The official chipset drivers should utilise the motherboard to its best capacity and ensure you get the maximum performance you can.
That's just a very rough overview from my understanding, someone correct me if I'm wrong - but the bottom line is if it's working fine as it is then you can just leave it like that