I put MB Quart Refrence Components in my wife's car, and they sound incredible. I have also used Infinity Refrence components as well.
As for coaxle, I am using Pold db's and Infinity Right now. Very happy w/ both. I am also a fan of Pioneer, which may be the best bang for the buck speakers IMO. They are not quite as good as the others listed, but they don't cost near as much, either.
And like Carpe said, components are separate woofers/tweeters. 4 ways have all (woofer/mid/tweeter/supertweeter) in one package.