A low level of computer literacy has often been hypothesized as constituting a disadvantage in knowledge acquisition. However, within the field of computer-supported inquiry learning systematic investigations of these purported relations have not been conducted. This classroom study investigates the role of computer literacy (procedural computer-related knowledge, self-confidence in using the computer, and familiarity with computers) as a learning prerequisite for knowledge acquisition, and analyses the learners' patterns of media use as processes that might explain this role. Thirty-seven students from two final classes of a secondary school worked in pairs on the project "How far does light go?" in the Web-based Inquiry Science Environment. Findings did indicate significant relations of neither procedural computer-related knowledge nor self-confidence in using the computer to knowledge acquisition. However, students with greater familiarity with computers acquired significantly less knowledge. In the light of the patterns of media use, these findings might be explained by different navigation styles adopted by students with high and low familiarity with computers: students with high familiarity with computers exhibit more shallow processing strategies ("browsing") which are less functional for learning.