if you say that ur sounds work in control panel then there is no need for any driver as the same is present. To further check if your sound device is present you can check with any media player to re-confirm the presence of sound driver.
If it is only the startup & exit of the windows then go to>control panel>sound and devices>on sounds on devices properties > sounds> in the programme events scroll down & YOU will find WHAT YOU NEED.
Although my sounds work in control panel/media and sounds, the windows start up and exit music don't play when I start and exit. My sound card is SiS7012 which is on the Motherboard CD. When I just did a custom Windows update it said I could download C-Media AC 97 Audio Device. Should I do that?