Illegal immigration

I was watching Kansas City Week in Review this morning on PBS, and they had a fiery roundtable on illegal immigration. Most of the talk was pretty emotionally charged, but an interesting comment came out of one Kris Kobach, the most recent loser in our 3rd District race to Congressman Dennis Moore.

He mentioned that the arguments currently being made by business (take away our cheap hispanic labor and the economy will collapse) is the same argument that was made in the mid 19th century by plantation owners (take away our cheap labor/slaves and the economy will collapse). So the question is: How necessary is this labor (cheap or underpaid labor) to the backbone of our economy, since we have proven over time that slavery was not necessary to the 19th/20th century economy?