parents and growing up

[smiley21]

What do you do when you are trying to grow up and be an adult, but your parents won't let you?
I am out of college and still living at home with my mom and sister. I want to move to another city and start a career. My parents do not think that I am ready. They said that if I go, they will not support me in anyway. In other words, my leaving will turn my parents against me. I do not know what their problem is. I am 24 years old, so I think that is considered old enough to make my own decision. They are trying to make me feel guilty by insinuating that I am ruining my life if I don't listen to them.
I don't want them to be against me, but I want to start my own life. What would you do?