The old correspondence course has stormed into the high-tech age—and it’s proving to be a bighit. As many as 4 million Americans are now buffing their professional credentials by padding overto their PCs and plugging into “distance learning.” Need to get over your fear of public speaking?Front Range Community College near Denver will teach you the techniques over the Internet.(Note: There’s no escaping four live on-campus presentations.) How about accounting? GreatBritain’s Open University, with nearly 150,000 students worldwide, offers a highly regardedcurriculum. The University of Massachusetts at Dartmouth recently started an online course inwriting for the World Wide Web.