The Ethernet Controller, and any other device, will not appear in the belarc report if the driver is missing. But what it does show is the make & model of the motherboard on which the ethernet controller is mounted. It's the manufacturer of the motherboard which can supply the driver, and it will be available on their website.
(incidentally, when you go through the update or install driver wizard in Device Manager, Windows only checks the Microsoft website not third-party websites. When no driver is found it merely means that the Microsoft website does not have it).
The Intel Ethernet driver (otherwise called a LAN driver) for your Intel D845GRG motherboard is here:
http://downloadcenter.intel.com/Deta...nal& lang=eng