I'm not sure that the problem is....
If you don't use an arcade monitor, you'll prety much have to use a TV or a computer monitor. Although no monitor can reproduce EVERY game perfectly, guess which one out of the three can do the most, the most accuretly.
what games can you not play at 15Khz? My monitor can reproduce vertical and horizontal games, classics and new games, windows/linux desktops, windows games (linux games like tux racer, i assume, but havn't tried yet), even vertex games without difficulty. The trick is to get enough native resolutions so that you can get games fullscreen without stretching them.
If you have an arcade monitor, I would recommend Ultimarc's ArcadeVGA card... easy to set up, pretty fool-proof and nice looking.