Trying not to fry them

Plug adapter for Argentina and Uruguay?

I am going on a trip to Buenos Aires, Montevideo, and Iguazu Falls (Argentinean side). I'm going to be staying in business-class hotels (Sheraton Montevideo, Hotel Emperador Buenos Aires, Iguazu Jungle Lodge). I am taking my iPod and the battery charger for my Canon SD870IS (both dual voltage/frequency), and I am researching what type of plug adapter I will need. It looks like most places will either have this two-prong plug, which is similar to the plug used in many countries, or this three-prong plug, which is similar to the plug used in Australia and New Zealand. Just when I think I will be able to get by with a simple universal adapter, I notice this warning regarding the three-prong plug found in AR and UY: In Argentina and Uruguay, the neutral and active wires are reversed from what is used in other countries. Now what? Should I just wait until I get there and buy a plug adapter at the airport? Any first-hand knowledge or general advice would be much appreciated.