This paper presents the Virtual EZ Grid project, based on the XtremWeb-CH (XWCH) volunteer computing platform. The goal of the project is to introduce a flexible distributed computing system, with (i) a non-trivial number of computing resources infrastructure from various institutes, (ii) a stable platform that manages these computing resources and provides advanced interfaces for applications, and (iii) a set of applications that take benefit of the platform. This paper concentrates on the application support of the new version of XWCH, and describes how a medical image application MedGIFT utilises it.