got a GeForce4 MX 420, downloaded and installed the latest driver 99.73, plug in a VGA splitter, try to get dual display on 2 monitors so I can extend window into the 2nd monitor. It keep seeing only one display, whatever the 1st monitor shows, it also shows on the 2nd one. Any solution you can help ? thanks in advance.
Your card does not support dual display tech which is advertised today. You need a card which supports two displays but I doubt if it's available in the AGP category.
So, most probably it's time you upgraded you rig.
Seeing the specs for you rig would be interesting, since I used to have that card way long ago.
You can get a dual monitor card for AGP, however you need to make sure that your card supports it. Many vendors will use the same chipset, but one may only have out output on the card and another can put 2 on.
I installed several APG nVidia FX5200 cards with dual-outs and they run fine, you probably just had the wrong idea on how dual monitor displays work.