Chip set drivers for the motherboard would be the most critical first driver to install to ensure best possible outcome to allow the operating system know what the motherboard is capable of.
Usually drivers off the original cd are good enough, i wouldn't worry too much unless there are major issues recorded, otherwise no harm in downloading an updated version just for the sake of it.
2nd driver to install can be anything, from lan, sound, video to other addons - it is recommended installing latest versions but i wouldn't concern yourself using original drivers (except for video drivers) if you're not experiencing any problems.
People have all kinds of ways and priorities, this is mine, as long as the chip set driver is installed first and directx along with the video driver all should be working properly
After that its more or less trial and error and getting to know your rig before making any further tweaks based on reliability and performance should you look for bios fixes.