im thinking its the graphics card driver you need. windows 98 should be able to use its own driver for the monitor. click here says its plug and play.
try downloading this its called everest home edition click here install it and click 'computer/summary' and scroll down to find 'display/video apadter' or similar and note the make and model. may help. If thats not listed check for 'display/GPU' info may help.