yeah, i'd take it easy with the new shoes especially if the model is different than what you've been running in.
IT band injury is probably the worst of all, apart from a stress fracture i guess. first time i had it was just for a few weeks (happened during a marathon) before i was able to run again, but the second time lasted for half a year. i just gave up on running for a while.
just came back from a 3 miles in the cold. i'm taking it easy after 2 months of no running (and gaining weight. hehe). love my new jacket!