This is an old question but here is my solution to the exact problem if you want to use the USB driver you got from the SDK manager, seeing that the documentation @MeowMeow linked is not too current:
- Open "Device Manager" on Windows
- Find your device, mine was listed under Android Device > Android ADB Interface (I have an unbranded android device, yours might be different)
- Right click on your device and select "Update Driver Software"
- Select "Browse my computer for driver software"
- Select "Let me pick from a list of device drivers on my computer"
- There will be a "Have Disk" button below your available Drivers, Click on it.
- On the "Install from disk" Dialog, browse to your path_to_sdk/extras/google/usb_driver folder. There should be a file named "android_winusb.inf", select it and click "Open" and select "Ok"
- You should now have a new Android ADB Interface'Model' by Google inc.
- Click "Next" and agree to everything till you are done..
Simple...no need for extra software, but you will need to have installed the USB driver from the SDK manager (like the guy who asked the question) before following these steps.
As a side note, I am running win 8..the steps might differ for you :)