Two C's will not kill you, especially if you are able to make up the GPA somewhere else. A W will also not ruin everything, but you will have to be able to explain it during an interview. I have two C's and a W on my transcript and have an acceptance already.
However, a third C could do a lot of damage. If you think that a class will come up that you might get a C in, you could be forced to drop that one to maintain GPA. Then again, multiple W's on your transcript look worse than C's. Also, remember the most schools like to see an upward trend. While this does not mean that you should get a 2.0 freshman year just so your 4.0 junior years looks better, it does mean that having somewhat low freshman GPA can be counterbalanced by your classes later in college.
Best of luck!