Step by step
- Download Android SDK
- Run <sdk_loc>\tools\android.bat
- In the Android SDK Manager, scroll down to "Extras" and select "Google USB Driver". Install it.
- Open the Device Manager (tap the Windows button and type "device manager" to search for it).
- Right-click the Nexus S and choose "Update Driver Software..."
- In the dialog that pops up select, "Browser my computer for driver software"
- Browse to <sdk_loc>\extras\google\usb_driver
- Click next until the driver is installed