Look at your monitor manufacturer's website perhaps? (and/or whomever makes
your video card)

Download and install the latest video card drivers from the video card
manufacturer's web site..

You have a video card that allows you to see on your screen, a sound card
that allows you to hear your PCs sound output and so on.  Visit those
manufacturer web sites for the latest downloadable drivers for your
hardware/operating system.  Always get the manufacturers' hardware driver
over any Microsoft offers.

How do you know what hardware you have in your computer?  Break out the
invoice or if it is up and working now - take inventory:

Belarc Advisor
http://belarc.com/free_download.html

EVEREST Home Edition
http://www.lavalys.com/products/download.php?pid=1&lang=en

Once you know what you have, what next?  Go get the latest driver for your
hardware/OS from the manufacturer's web page.  For example, let's say you
have an NVidia chipset video card or ATI video card, perhaps a Creative Labs
sound card or C-Media chipset sound card...

NVidia Video Card Drivers
http://www.nvidia.com/content/drivers/drivers.asp

ATI Video Card Drivers
http://www.atitech.com/support/driver.html

Creative Labs Sound Device
http://us.creative.com/support/downloads/

C-Media Sound Device
http://www.cmedia.com.tw/e_download_01.htm

Then install these drivers.  Updated drivers are usually more stable and may
provide extra benefits/features that you really wished you had before.