Mobile handheld devices such as PDAs and smartphones are increasingly being used by service providers to deliver application functionality similar to that found in traditional desktop computing environments. However, these handheld applications can be quite slow and often lack important functionality compared to their desktop counterparts.We have developed PASSPORT, (PDA Application Streaming Service PORTal) a thin-client solution that leverages more powerful servers to run full-function desktop applications and then simply stream screen updates to the PDA for display. PASSPORT uses server-side screen scaling to provide high-fidelity display and seamless mobility across a broad range of different clients and screen sizes, including both portrait and landscape viewing modes. PASSPORT also leverages existing PDA control buttons to improve system usability and maximize available screen resolution for application display.We have implemented PASSPORT on Windows PDAs and demonstrate that it can provide superior application performance and functionality compared to the traditional approach of running applications directly on handheld devices.