Sulfur smell? Almost sounds like something bloomed and then died in there? Have you tested the water at all, like a baseline test or something? I too agree that you shouldn't use that water. Strange.
It is the pressurized tank that goes with the RO/DI unit. The water only smells right after coming out of the tank. If it goes through the unit but not the tank it doesn't smell or if it sits for a day inside a plastic water jug (not air tight) it doesn't smell. I tested the water coming out of the tank and it is ammonia 0, nitrite 0. For reference my tap water is also 0/0/0.
I'd probably get the one that is made to go with your system as it's price looks good. However, AWI often includes a TDS meter with their units (such as Typhoon III) and they sell different kinds as well: http://www.airwaterice.com/c=kdiXAk5CnGNQYLcVZw3cT3ZlW/category/10/