Mobile computing systems are provided having an ultra-mobile PC and a detachable wireless communications module operable as phone and a short range and long range wireless data link. In one embodiment, the wireless communications module is capable of synchronizing data with the ultra-mobile PC. Another embodiment provides parasitic charging of the wireless communications module from the ultra-mobile PC battery for extended battery life. Another embodiment provides ability to synchronize data to and from the ultra-mobile PC even when it is powered off. Another embodiment provides drag and drop capability between the wireless module screen and the UMPC screen, which may provide application or operating system data transfers.