Magneto-transport measurements have been carried out on networks of purified single-walled carbon nanotubes. The features observed include positive magnetoresistance, negative magnetoresistance, and magnetoresistance oscillations. These features are found to depend sensitively on temperature and applied electrical current. The experimental observations are interpreted in terms of antilocalization induced by spin-orbit coupling, weak localization, electron-electron interactions, and electron interference (Aharonov-Bohm effect).