Don't need a converter to use a desktop monitor (Score 0)

The 360 can output vga without conversion, you can buy the cable (1st party) anywhere. Most modern monitors can handle hd modes supported by the 360 so it works out quite well. The cable includes rca plugs for sound, you can probably find a ready made converter to go from rca to a 3.5" jack for headphones at any radioshack.