Here's a great article from the Christian Science Monitor about government spending vs. charitable giving, and the response to Katrina.

While they say that private charitable organizations are more effective, they don't really delve into how much more effective they are. From an article at the Foundation for Economic Education:

"Several years ago it was calculated how much would be required to lift every man, woman, and child in America out of poverty by simply giving them money. The figure came to one-third of what was spent on poverty programs."

So this, combined with the CSM article, only reinforces what we should already know: government programs are wasteful, ineffective, and stifle people's natural charitable instincts. Furthermore, the state forcefully taking money and giving it to the poor is not charity at all -- not any more than it would be charitable for me to steal $20 from you and give it to a homeless man on the street.