First be sure the cables from the speakers to the sound card securely
connected.
Second, open Control Panel, open Sounds and Audio Devices. Only soundcards
that support having the speaker icon in the notification area will have the
option listed here and it is not selected by default. If you wish the icon
to appear in that area, place a check next to "Place volume icon in the
taskbar," click apply and ok.
Now, while you are in this applet, click Advanced under Device volume, be
sure noting is muted and be sure the sliders for volume area about half way.
If thing check out, in Control Panel, open System, go to the Hardware tab,
click Device Manager, be sure there are not red or yellow warnings.
If the lack of sound is a recent issue, you might try using System Restore
to take you back to a time prior to when this began. Start\All
Programs\Accessories\System Tools\System Restore.
If this doesn't resolve it or you've never had sound, check the soundcard
manufacturer's website for the latest drivers for your card and XP. If
unsure of the type of soundcard, it may be listed in Device Manager or check
your system's documentation.