Rush is a mutual selection process. Simply because your friends at other schools are Delta Gammas does not mean you are assured a bid to DG or even that DG is the right sorority for you. It might not even be the group your friends would choose if they went to school there...chapters are different at every school even if they're not far apart geographically.
It would be nice to be in the same sorority a lot of your friends are in but their affiliation really has no bearing on your rush.
Here are some threads on Ole Miss.
http://www.greekchat.com/gcforums/sh...threadid=40544
http://www.greekchat.com/gcforums/sh...threadid=40209
http://www.greekchat.com/gcforums/sh...threadid=24081