If it's not a VGA connector than it's the mac video connector. I don't have one front of me to count out the pins, but it's larger than a standard VGA.
You could either look around in surplus stores for an old apple monitor or you can hit up a local computer store and ask for a mac to vga convertor. A lot of the mac video card dealers use to provide these adapters because so many still had the apple specific monitors.
If you don't want to get the adaptor, then there is always the option to buy a new video card.