Intel has released a fabulous tool that not only scans your PC for devices but also updates the drivers in one fell swoop. Take a look at the Intel Chipset Installation Utility. This tool eliminates most of the dreaded UNKNOWN DEVICEs on a fresh install of Windows.
After your chipset drivers are installed, you may find the generic Intel Driver Update (Finder) Utility to be handy.
On a related note, if you have a PCI SIMPLE COMMUNICATIONS CONTROLLER sitting in you Windows Device Manager with a bang on it, you likely need to download install the Intel Management Interface Driver.