Well, under Unix, you could use SoX (amongst many others, I'm sure) and write a simple script around it to grab the first however much of each track using its trim function and write it to a new file. But I don't know if you can find it under Windows.

Actually, you can. There's a binary of it right on that page. I don't know much about scripting under Windows, though. Maybe someone else could help you there.