This chapter introduces the concept of multi-modal interaction and our findings related to the development of biomedical applications for two different projection modalities: virtual reality and desktop. The case study for this research is a simulation system for vascular reconstruction- the Virtual Radiology Explorer (VRE). The VRE is an interactive simulation-visualization complex aimed to help in making diagnosis and treatment planning for vascular disorders. To make the system functionality available both in virtual reality and desktop settings, two versions of the VRE have been implemented. We present their qualitative comparison analysis in respect to the interaction capabilities provided. To check, which projection modality complies better with the expectations of potential users of the VRE, and to find out the possible place of the VRE in real life environments, two user groups- vascular surgeons and interventional radiologists – have been interviewed and their daily activities observed. Users ’ needs, everyday tasks and preferences have been analyzed; the main results are summarized in this chapter. Among others it has been found that the combination of virtual reality and desktop projection modalities within the same interaction-visualization environment may help to satisfy a wider range of the VRE users in comparison to the case, where only one projection modality is used. To finalise the chapter, we discuss three alternative solutions on how this concept can be deployed.