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.