I also loved Jennifer L's answer..
I think it is incumbent on us to do what we can, with the resources we have.
I'm thinking of my personal "hereo" in history. Her name is/was Stefania Podgorska. She was just a kid (16) when the Jews in her city (including the family she'd been living with) were rounded up and put in Ghettos. Her mother had been taken to Germany as forced labor, so now she was left alone to take care of herself and her little sister, a daunting task in an occupied and war-torn country. But she didn't let her own troubles blind her to the horror around her. For 2 years (until the end of the war) she singlehandedly hid and cared for THIRTEEN Jewish men, women, and chlidren in her attic, at the risk of her own life and her sisters. She is responsible for saving the lives of those 13 people. Now, if you put 13 saved against 6 million killed, it doesn't seem like she did much.. but she did what she COULD..(The Nazis liquidated the Ghetto, murdering or shipping out the rest of the Jews in the city shortly after #13 had come to live in her attic) I guarantee, to those 13, yes, she made a difference.
So, while yes, I agree that adoption may not be the "cure all" to the world's poverty problems... there are times (especially in war and aids-torn countries where there IS alot of REAL orphans) that it is necessary, and DOES make a very positive difference to those children.
I hope I made some sense...
The task to "Fix the world's problems" is daunting.. All each of us can do the job given to us. Whether we have the recourses to save thousands, like Oscar Shindler did... or only 13.
I'm not talking about adopting as "saving" orphans.. please don't get me wrong.. As a PAP, I'm not going into it with a "savior" complex.. I'm talking about helping those in need in ANY WAY, as I understand the sincerity behind your question. I'm talking about what you're talking about... how to save the world... how to help those orphans.... whether it be adopting, helping the family be able to support them, helpnig them stay in their culture by providing housing, education, etc, to help them better themselves... I think there's no "one solution" that is going to work for every situation.
Stefania only saved 13 Jews from the death camps... but those 13 grew up to have children, grand children, and great grandchildren.. Some of which Stefania herself bore (she married one of the Jews she hid).
Think of this: If just a few hundred thousand other people did what this kid did, instead of doing nothing (as many did) there would have been no Halocaust. I think when we look at it that way, we have our answer..