I used to have a cga to vga converter board and it worked very well.  I used it with a neo-geo and mortal kombat 2 with no problems other than having a little trouble with centering the picture on MK2.  I could get it to either cut an inch off th e bottom or an inch off the top.  The one I had looked like the one Yaton sells on arcademvs.com, but I don't know if it was the same model.