VGN-FZ180E sound volume playback question

I own the Sony VGN-FZ180E laptop. During normal use when I turn the speaker volume up all the way using the laptop volume control and then push the sound slider up all the way in Windows Vista, the sound playback volume is weak.
On the other hand if I go into the control panel and click on the sound icon and select Speakers as a playback device then click on configure, I can test the laptop speakers and the sound playback volume is very loud. Why is there such a big difference between the two sound playback volume levels?
How can I get the sound level volume playback on this laptop to be as loud during normal use as the sound playback volume level during the speaker configure test in Vista?
Somewhere in this forum someone suggested going into the BIOS to adjust the speaker volume but that option is not listed in the BIOS on this model.
Your help with this problem is much appreciated.

 

For loud internal speaker volume, uninstall the Sigmatel audio driver, restart, and let Vista install it's default Audio driver. But there is one downside to this, you have to close the media player before connecting anything through the headphone jack and do the same before disconnecting for automatic sound switching.
Also switch the default Microphone in the playback devices, for the internal mic to be recognized when using the default Vista driver.

Note: The Sigmatel driver sounds adequate for external speakers, but too weak for the laptop's internal speakers.