if ur 15 k monitor can handle composite sync the easy and cheap route would be ripping a 5 dollar xbox 360 scart cable . it provides rgb , sync and audio l+r.
but why anyone is considering hooking up a 720 p console to a screen giving a flickering interlace picture is far beyond my understanding. build or buy a cabinet with at least vga input screen or better . i m using my box with naomi vga , dell ultrasharp 20 inch cocktail , nec xm2960 and sony kdm 32 flat tv.