Can I be a member of all the sororities?

Hey Greek Advisor,

My name is [female freshman], and I am currently a freshman (initiated in fall 09) to Alpha Alpha Alpha Sorority. I love
greek life and I want to continue, but after a semester I just don't
think Alpha Alpha Alpha is the right sorority for me..I just wanted to ask what the policy-if there is one-about switching. Would I be able to rush in the fall '10 if I resigned from Alpha Alpha Alpha? Or would I be bound to them, and have to go without a sorority completely? Or would I have to wait a year+? I don't know what to do, because I don't want to get stuck in a place where I can't even rejoin greek life-
meaning being older and not having a very good chance of getting into a sisterhood..because thats the last thing I want. I have found greek life to be so stimulating and amazing for me getting involved on campus and bringing me closer to people my freshman year- Could you please write me back and tell me what my options are? Thanks so much.