All incoming freshmen majoring in computer science at the University of Minnesota Duluth (UMD) are required to purchase a handheld computer with wireless capability (HP/Compaq iPAQ). The integration of these devices into the CS1 curriculum was primarily achieved by authoring and distributing a number of applications written to allow students to interact with visualizations of key concepts using their handheld computers. Downloadable from the campus wireless network and used in class (large lecture and discussion) the contribution of these applications to the course was substantial. The handheld computers and accompanying visualization software served as course companions, instantly providing meaningful content and engaging instruction anywhere the student went, on campus or off. Students rated the concept visualization software as the most useful aspect of the course. The success of this initiative leads to several important conclusions about the relationship of handhelds to laptops as learning tools, the importance of visualization software and the successful integration of companion technology into the CS1 curriculum.