Since you're using a standard res monitor, 640x480 is outside the usable resolution. If you want those higher resolutions, then you would need a tri-sync, but they are pretty pricey. What kind of games do you plan on emulating? 90% of the arcade games out there are standard res. The other 10% either can't be emulated or don't work well under emulation. I'd say just stick with the standard resolution. Tri-sync is only worth it if you plan on running real high-res games (Naomi, Atomiswave) and standard res games.