Are we just talking INF update here or specific drivers? If it's just about the INF update, you can (and probably should) install it, since it is no more than an updated text file, which tells Windows, what sort of chipset the motherboard uses (PCI bridge, AGP etc.). *NO* new drivers are installed, unless you've got the combined package with Intel busmaster drivers. The reason for the size of the INF update is that even tough it is a simple text update, the installation software that does it takes up a bit of space.
So, if you want to make sure that Windows detects all of the (Intel) components on your board correctly, you should install the update. Again, as for the busmaster drivers, I'd suggest to stick with the built-in Microsoft versions unless you experience problems.
Hope that helps...