BTW, yeah you should have no problem hacking a normal vga cable to the r,g,b,sync of the monitor. You should find plenty of diagrams on here and the web to show you just which pins you want...
If your gonna use a 'normal' graphics card, you'll need one that can output at 15khz. I use an old ati rage128 in one of my cabs with AdvanceMame, and AdvanceCab...You'll need to run some kinda software like this, or Powerstrip to adjust the videocard rates.
A far easier way to go is get Ultimarc's ArcadeVga card.
hope that helps
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