Wow, thanks for all the help. This must be the most helpful forum for newbies ever!

Anyway, I think I've confirmed that it's SXF (though I will give a huge to expedia's customer service reps on that score, one of whom insisted that I would be flying into the new BER, much to my amusement).

Perhaps I should have been clearer in my OP; I'm actually trying to catch a long-distance train across Germany. My flight lands at 17:10, and the deutschebahn website lists a train leaving Berlin-Schönefeld Flughafen (I presume that's the station at the SXF that david7031 referred to?) at 18:50.

So, I'm a bit pessimistic, but is there anyone out there who thinks that I might have a shot at getting me, my wife and two boys out of the plane, grabbing our bags from the check, hopefully walking right through customs and right over to the train station and catching a train west towards Hannover in 1 hour and 40 minutes?

If I miss the 18:50 train, the next option is at 20:22, and that puts me pulling into my final destination past 1 am (not something likely to make for happy 5 year-olds). I suppose we'll do that if we have to, but I'm wondering if we have any shot at the earlier train, and thought maybe someone on here who has done it could give me a guess at my odds.

The other option is taking a taxi straight into town to the Berlin Hbf, skipping the airport link. That train leaves at 19:48 from the Berlin Hbf, and is the same one I'd be on if I get the train at the aiport at 18:50. Would my chances of that be better (17:10 to 19:48 from airport to Berlin Hbf)?

Thanks again for being SO helpful, in advance this time. Oh, and while I'm at it, has anyone actually done Germany by train? Do I really need to prebook the train tickets online, or am I OK doing it when I get there (I don't want to prebook and then miss the train, obviously)? Promise I'll stop bugging all of you now.