a. If you dont want to use the ToolKit to install the drivers then the best best drivers to try are PdaNet for Android, download and run the
32-bit Windows 7/Vista/XP or
64-bit Windows 7/Vista and follow the instructions to install (selecting Samsung as your device manufacturer if asked).
You can remove pdanet for Android from your phone and pc at a later time without removing the drivers.
b. After the drivers have been installed disconnect the usb cable and shut down your phone. Keep holding the 'Volume Up' and 'Volume Down' buttons and press the 'Power' button to boot the phone into FastBoot Mode.
c. Goto your Control Panel on your PC and open the Device Manager. You want this open so you can see the FastBoot driver is installed or so you can install it manually.
d. Connect the usb cable. In the Device Manager a new item called 'Android 1.0' should pop up and then the driver should install automatically. Once it is installed you will have a new section in the Device Manager called Android Phone without an "!" meaning its installed correctly.
MAKE SURE YOU ENABLE USB DEBUGGING IN SETTINGS, DEVELOPER OPTIONS BEFORE CONNECTING THE USB CABLE IN ADB MODE SO THAT THE PC CAN DETECT THE PHONE PROPERLY.
Note 1: If the driver doesnt install automatically then double click on the Android 1.0 item, then click on the driver tab and select 'update driver'. Select 'browse my computer' and browse to the Google Nexus 7 ToolKit\driver folder. Drivers should then be installed correctly.