Yes!!

You will have to leave the country to adjust, but it's definitely possible. As hef mentioned, you are going to need to file a waiver for your illegal presence.

I'm actually going through the process right now. I entered illegaly as a child, have been married to a USC for almost 2 yrs, and I'm about to leave to Mexico in a few days for my appointments.

Are you looking to hire a lawyer or doing it on your own? Check out this website: http://immigrate2us.net/forum/forum.php

Good luck!! =)