What's wrong with Immigration?

Is immigration really that bad? Why? I'd rather give immigrants here a job if they will then spend the money here... it would help the economy more than companies sending the factory down to mexico.  At least if they live here, and buy things here, it will help the economy here, rather than the alternate... as I said.. our companies go searching elsewhere for cheaper labor.  What do you all think?

Lets not commit genocide on the mexicans, but lets just invade their country and establish a better government, then take their resources as payment so we don't have to pay taxes for the war. 

Some would say we are robbing them of their resources, but who cares? We are just doing the job all those immigrants wouldn't do for themselves anyway.

Plus, Mexico would be real easy to invade.  Ground forces could just march right in by land.  Iraq, on the other hand, is on the other side of the world, and accross an Ocean, and maybe a desert and a sea or something.  Lets just go for Mexico, its much easier, and would help with our immigration problem.