Stop over-thinking; because she talks to you on AIM doesn't mean she doesn't like you, dude.
Like, maybe she's scared to talk over the phone. It's easy to carry a convo on AIM; both people are less reluctant to tell what they really feel.
You have complete control over the direction of your relationship with this girl - AIM...MSN....etc. cannot possible change that; only you can.
I use AIM to keep in touch with people. I don't use AIM to "hang out" or to carry out long convos... only in limited circumstances, but when I talk for a long time on AIM; I build interest. You should work on that.
However, arguably, the best thing for me, and for anyone else (like you) is to arrange a meeting - hang out with her.
IM her, Call her, and ask if she wants to chill. If yes, then good; if no, then go do something else.
She'll come to you once you establish that if she wants you. We don't live in an old fashioned world; girls know how to get guys, just as well as guys know how to get girls.
good luck to you
