The electronic field guide of the invention presents multiple data items to an end user, via the display of a stationary computer, and allows the user to select particular ones of the multiple data items that are available. Multimedia data files corresponding to the selected items are then downloaded onto a portable computing device such as a personal digital assistant (PDA). Thus, the user will have access to a subset of the overall data on his portable PDA. This invention may be used, for example, to provide electronic field guides in such applications as bird watching, where the multimedia data files contain the images of birds, audio files containing their songs, and text data. The main data may be stored on a CDrom, be made available over the Internet, or be provided in some other manner.