The most important thing: download drivers for the video card that's in the machine. The monitor is less important.
You can have a look in either the specs/documentation of the machine or Device Manager to see what the and model of the video card is. Or download a free program called Belarc Advisor (search for download belarc in google) to find out. Use the Windows 98 drivers, of course.
But they should be available on the Dell site either, as drivers for the XPS T500.
Generally, the video card driver will support any monitor.
Hope this helps.
I need help with downloading display drivers for a Dell E770 standard display. I have a Dell Dimension XPS T500. I did not see the display model number under drivers on the Dell website. I just spent an hour on Dell Chat only to find out they would not give me the information because I couldn't give them the phone number of my old address. I've moved several times and don't remember. I am running Windows 98.