Getting an unsigned driver error while using 6303_Vista_PG537.zip 's drivers for Windows 7?

Download Realtek's Windows Vista / Windows 7 Drivers here:

FILE: 6305_Vista_Win7_PG537.zip (link to download)
SIZE: 31,126,033 bytes
SHA-1: CF80B465D33B2A40B40EFF48EB8DAA60FC6EC155
Includes the 32-bit and 64-bit drivers