The study of gender differences in Computer Science (CS) has captured the attention of many researchers around the world. Over time, research has revealed that negative stereotypes and 'myths' about the cognitive skills, academic abilities and interests of females in CS do exist, deterring females from entering the field. Thus, this study aims to shed light on the aforementioned stereotypes and 'myths' by investigating gender differences in terms of student preferences and performance in the undergraduate courses included in the entire curriculum of a CS department. For this purpose, a case study was designed, exploiting data from a CS department in Greece; more specifically, 89 graduate degrees were quantitatively analysed. Regarding performance, the analysis of the data revealed that--apart from in a few courses--there are no statistically significant differences between the mean grades of male and female students in most of the curriculum courses of the CS department in question. Concerning student preferences in CS courses, few gender differences appear to exist. At a statistically significant level, males preferred courses related to hardware and software engineering, whereas females selected courses related to theoretical CS, humanities and social sciences.