Those are not examples of the core-periphery structure I was talking about. Russia and China are not at the periphery of the world economy. Russia is a once-superpower, and China is pretty much a superpower now. The core-periphery structure is one of dominance and exploitation. I'm talking about developing nations where labor is cheap; those who produce goods for the first world - i.e. sweatshop workers in impoverished countries, or countries that grow things like coffee and bananas for people in America and Europe.
There are rich elites within the periphal nations, who serve to maintain this power structure, support the core, and also benefit from this relationship.
Of course, this is true to an certain extent.
$70,000 a year is a livable income in America. But if you had an income of $70,000 US a year in Thailand, you would be able to live like an absolute king! That's equivalent to 2,205,330 Baht per year, and the purchasing power of the baht within Thailand is greater than the purchasing power of the dollar within America - i.e. you can buy a lot more stuff for a lot less money in Thailand.
The thing is, the extent is this - you don't see many people from America moving to live in Thailand, because although you can do a get more with your money over there, the overall standard of living of the general population is lower. People like to stay around other people who are more alike. If you were living in Bangkok, even if you were rich, you'd be rubbing shoulders very closely with the dirt poor every day, the bargirls & prostitutes, the peasants, etc. If you were living in suburban middle class USA, you'd be rubbing shoulders with people who have living standards just like yours. You'd feel more comfortable amongst that general way of living, with people who are more like you. That's why Thailand is more of a place for a holiday than a place to actually go and live, for the majority of Westerners.