Ad-hoc wireless networks, which use ad-hoc routing methods may prove a good solution in certain applications, especially where networks have to be constructed where there is no possibly of creating a network backbone, and in emergency situations. They may also lead to more flexible networks, which require reduced configuration, and allow for optimised routes. There is thus a requirement to use mobile devices as intermediate routing devices, which forward data from one device to another. One of the best methods is to run a proxy server on the mobile device, as it allows for a simple implementation on the device. A key factor in this is determining the fitness of a mobile device, especially a limited one, such as a handheld PDA. This paper discusses the metrics that could be used to assess the potential of devices and their environment to route certain types of data, and presents results from iPAQ devices using a range of differing operating systems. It shows how performance of a proxy device varies depending on several factors including the Java environment used, and the operating system used. The paper shows that Linux versions for handheld devices out-perform the equivalent Windows systems for the key performance metrics for proxy devices, such as battery usage and network performance.