Transition from an existing IT system to modern Web technologies provides multiple benefits to an organization and its customers. Such a transition in a large organization involves various groups of stakeholders who may prioritize differently the requirements of the software under development. In our case study, the organization is a leading domestic company in the field of electricity power. The existing online system supports the customer service along with the technical activities and has more than 1,500 registered users, while simultaneous access can be reached by 300 users. The paper presents an empirical study where 51 employees in different roles prioritize 18 software requirements using hierarchical cumulative voting. The goal of this study is to test significant differences in prioritization between groups of stakeholders. Statistical methods involving data transformation, ANOVA and Discriminant Analysis were applied to data. The results showed significant differences between roles of the stakeholders in certain requirements.