I checked the Desire S specs. In 2g mode it's a four-band phone, in the frequency ranges 850, 900, 1800 and 1900. According to a wikipedia article, you're in luck as North America uses two of those. However, the 3g bands that the desire S uses, 900 and 2100, don't appear to be used in the same area, again according to wikipedia. Not being able to use data could be a blessing in disguise, cost-wise! Of course, you should be able to get plenty of wi-fi access over there unless you're going to chop down trees or hunt moose!