Whenever you install Windows you also have to install all drivers, including chipset, LAN, sound and video. Did you neglect to install any of these others too?
If you have a self-built or custom built PC, go to the motherboard manufacturer's website to find the appropriate drivers. If you have a PC made by a major manufacturer like HP, Dell, Acer, etc., go to their respective websites for your drivers. If you have a separate graphics card, you should go the graphics card chip maker (example, AMD/ATI or nVidia) for the appropriate driver.