This paper presents an empirical evaluation of mouse-based interaction as an alternative to traditional VR controllers in seated virtual reality (VR). We introduce a mapping of standard mouse actions to 3D object selection and manipulation and report findings from two controlled user studies. In the first study, we compared a VR controller against our mouse-based method for selection and manipulation tasks. Results show that the mouse consistently achieved higher precision and lower error rates, while maintaining comparable task completion times. Motivated by prior evidence on scaled interaction techniques, our second study investigated mouse interaction in a productivity-oriented scenario where users could combine 3D manipulation with a 2D adjustment panel. Results again demonstrated that mouse-based interaction provided superior accuracy and was rated significantly higher in usability and workload measures. Together, these findings establish the mouse as a viable and effective input device for seated VR contexts, offering both familiarity and precision advantages over controllers, particularly for professional and productivity-focused applications.