Cannot install sound driver - Intel CMI 8738 6-Channel 5.1 Surround Sound 3D PCI Sound Card (RETAIL BOX) - CM8738

If your computer came with a motherboard disc the sound drivers could be on it
click start control panel administrive tools computer management device manager scroll to sound video and game controllers you might see a yellow question exclamation mark? ! or a red X Right click to reinstall drivers
if you dont have a disk with the drivers you will have to download them

http://www.boxdrivers.com

using this link you will be able select your drivers
http://download.cnet.com/Realtek-AC-97-Driver-Windows-98-Me-2000-XP-2003/3000-2120_4-10238712.html
Realtek AC'97 Drivers & Applications. The package includes: Driver/Application Setup Program; RtlRack for Win98/Me/2000/XP and AvRack for Win95/NT4; Realtek Sound Effect Manager. DirectX 8 is required to enable advanced features.

http://download.cnet.com/Realtek-AC-97-Driver-Windows-Vista-Windows-7/3000-2120_4-10962344.html

http://download.cnet.com/Realtek-High-Definition-Audio-Codec-Windows-Vista-Windows-7-32-bit/3000-2120_4-10788600.html free sound drivers
Realtek HD audio driver package. The package includes: driver setup program, drivers for Vista 32-bitedition.
if these arent right you will find free sound drivers
http://download.cnet.com/2000-20_4.html
on the home page you should see a search tab just type in what you are looking for
(be precise)but don't use numbers or / - also the download software finder under that there will be a list place a tick in the box of any one you want/need
hope this help you