Being a white guy...it's difficult to say how I'd instruct my child in your circumstance. But I think it would do him more good to downplay the racism in the world as minor and indicative of uneducated people, and instead accentuate accomplishment, the good nature of most people regardless of race, and the strength that comes from individuality.
I don't know your philosophy in particular, so this is a generalized statement not necessarily applicable to you, but I know some minority parents feel that warning their child about racism and the expectation that they will be discriminated against because of their skin color somehow protects them, but I think it has the risk of instilling an inferiority complex and sets a child up in a self-fulfilling prophecy scenario. I think it's better to give the child a sense that people that are like that are small minority of uneducated individuals that you have to try to educate or ignore. I guess what I am trying to say is don't let your son internalize the venom being spewed by some idiots in the world.