If you're looking to be an extern for the summer, it really doesn't matter if you worked for state or fed'l court. Even if you want to be a fed'l law clerk once you graduate, no one will look at your 1L summer experience and give it too much weight. The purpose of your 1L summer is to give you something to talk about w/ the interview during OCI.
I'd look to work w/ a great judge. Like many of you have said, they can either just give you busy work, like updating the books, or you can be doing the same work that the law clerks do. In fact, early in summer, several externs have to take over calendar b/c the law clerks are out studying for the bar.