Does Illegal Immigration Hurt American Workers?

Currently, there are six million illegal immigrants in the American workforce (roughly 5% of the total.) It is often argued that these workers are taking jobs away from native-born Americans. However, it is also argued that illegals, rather than taking jobs, are indirectly creating them through the boost their labor gives to the economy. Additionally, Hispanics added an estimated ten billion dollars to the economy in 2002. However, this ten billion is out of a total of over three trillion.
Another often-used argument by immigration opponents is that if illegal immigrants were not so willing to take low-paying jobs, then working conditions in those professions would be considerably higher. Unorganized, "unofficial" illegal immigrants can work for miserable conditions for less than minimum wage. This argument is undercut, however, by outsourcing and the ability of American-based companies to relocate jobs to Asia and other worldwide. If these companies were forced to negotitate with unions that require higher wages and better working conditions, then they might just decide to pack up and leave altogether for a place with even more expendable workers with poorer working conditions.