Windows XP 

Properties panel. ( Get to this by first making 2 clicks on the "Speaker" Icon by the clock. If you do not have an  icon for the sound card on your task bar, go to Control panel, "SOUNDS and AUDIO Devices" then Volume sub menu and tick the " Place Volume Icon on the task bar." 
After clicking the Speaker Icon on the task bar a panel will appear with sliders. Select " 0ptions"  This will give you the display below.

This panel defines which controls appear in the playback and record panels.

Playback control panel ( Below)

Ensure all the tick boxes are not ticked ( Empty ) as seen below.

Recording Control Panel (Below)

Ensure Line in Volume - Select is set to ON as shown, to enable your audio to reach the sound card from your Rig.
This is just an example, you may need to use the Mike input instead. Some sound cards may be different from this.

Windows 98 sound card may look different to this so bear in mind the above terminology  and manipulate and adjust your 98 sound card to suit.