You might be able to get by relying on FAA flight service station specialists to tell you what you need without knowing much about where the information is coming from -- or clearly understanding the differences between the two kinds of weather information they're giving you. The men and women you talk with for a preflight weather briefing are professionals who can be counted on to tell you what you need. Still, if you know where the weather information is coming from and what's what, briefings will make more sense. You can also more efficiently find weather information with your computer using the Direct User Access Terminal (DUAT) system or the World Wide Web.