Arizona's Immigration Law: Constitutional or Not?

Arizona's new immigation law has been all over the news for the past few months. The country is largely at polar opposites regarding their opinions of this new law. Some people claim that this law is discriminatory, giving the police the legal right to practice racial profiling. I don't agree with racial profiling and I'm all for immigration, as long as the immigrants come here legally.
Illegal immigration causes all kinds of problems for our country. It hurts the U.S. citizens, when illegal aliens take jobs and use social services without having to pay taxes. Some (but not all) illegal aliens even commit crimes involving drugs and violence.
Even the illegal aliens who obey the law and are perfectly nice people are hurting the people who did come here legally. I like to think of it as going to college. Imagine spending 4 years going to college, paying through the nose for your education, working hard at horrid part-time jobs, and spending hours studying and doing homework all for the great reward of getting a degree. Now imagine another person can sneak into class and get the same result without having to do all the work involved. How fair is that? It happens every day. If I were a legal immagrant, I'd be pretty pissed off at these cheaters!
They might not know it, but illegal aliens also hurt themselves when they come here illegally. They have to worry about one day INS comes knocking on their door, fully prepared to take them away from their homes, and even taking them away from their children and sending them to a place they haven't been to in years. They are at the mercy of cruel employers who take advantage of them because they know their workers aren't legal. They can't feel safe from crime because if they were to contact the police they risk getting found out.
Nothing in life is free, and anything worth getting involves hard work. It might take years for someone to become a naturalized citizen, but the reward is well worth it. When you're naturalized, you don't have to worry about the police, you don't have to let people take advantage of you, you are a U.S. citizen.