I built a computer last spring with Windows 7, and needed drivers for video, USB and audio. Video worked, but was slow in games until I installed the official drivers. Needed the sound drivers for the front panel jacks to work, and the USB drivers for the front panel USB ports, the USB 3.0 port, and the "fast-charging" function of the mainboard to work.

It was easier than setting up OS X, but not by far.