This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
You are almost certainly being blocked by your proxy server, check the online documentation on how to configure around that. I'd also highly recommend the free "Maven The Definitive Guide" PDF by Sonatype