After downloading the LAN driver, you'll need to rightclick on it to Extract All, then browse the extracted files to Setup, rightcllick to Run as Administrator.
If this fails, click to Ethernet device in Device manager, Choose Driver tab, Update driver by browsing to the extracted files until it picks up the driver - may be in the x64 folder.
Driver Install - Device Manager
If this fails, follow this tutorial to read the Hardware ID off the Device properties, determine which make and model, then google it for Windows 7 64 bit driver:
Hardware Identification - Windows 7 Forums