The link above is to a program called PDAnet. Download it and install it to your windows pc. PDAnet is a program that is designed to allow you to tether your internet to your computer from your phone, but it is an easy way to install the drivers you need for ADB, as they are included in the install. if an adb driver is already on your computer, it might prompt u that there is already an existing driver. if that happens, just choose the option to reinstall the driver anyway.
Above is the link to Android SDK, just in case u dont have it installed yet. This will include the programs that you need including adb and fastboot.