I have just installed Windows XP Prof on a new desktop PC

I have no sound. The sounds & audio devices properties on the volume and
audio tabs indicate that there is no audio device for playback. USB audio
device is available for recording

I don't know how to install the driver for an audio device. I thought it
would have been included when I installed Win XP system.
I just want a default device as I have no special hardware. Can someone
point me in the right direction.