>I have not done this for a long time and I know it simple. Can any one know why NT 4.0 do not install by default the drivers for the sound card.
>

NT is not a Plug and Play OS; it's not concerned with installing the sound card drivers during the base install.

You'll need the NT drivers for your sound card; the NT drivers are distinct and different than those that ship with Win9x.

>And what is the best way to install the software for the sound card?

The vendor normally provides an install disk/CD for the installation. If this is an option, do it. The alternative is to use the Multimedia Control Panel Applet to add devices.