Here's a link to the UA bid list from the latest formal recruitment.
http://uanews.ua.edu/2010/08/ua-soro...-announced-11/
As you can see, every single sorority has new members from out of state - some even from (gasp) above the Mason-Dixon line.
Keep your grades up, participate in extracurriculars, and when the time comes, get recs. You have a while to think about all this though.
You're ahead of many women in realizing that just being a legacy does NOT guarantee you a bid - however, I would refrain from using phrases like "top 6" when discussing Greek life.