The Washington Post had an article touting Brazil's recent growth, implying that it is a growing regional powerhouse, at least in part at the expense of its neighbor. Actually, Argentina has been growing considerably more rapidly since 2003, the period discussed in the article.
According to the IMF, growth since 2003 has averaged 6.6 percent annually in Argentina. It has averaged just 4.2 percent in Brazil. It is worth noting that Argentina defaulted on its debt in 2001 and pursued economic policies that were widely condemned by both the IMF and most of the economic policy establishment.