Here is one interesting suggestion. Most of us know that Linux is a relatively secure operating system. But this security is relative and not all distributions provide the highest level of security that is possible for an operating system to provide. And there are people who fancy that their OS will not compromise even a tiny dot about security. When security is in the scene many instantly suggest OpenBSD. But OpenBSD, like all BSDs, has its drawbacks. All BSDs lag behind Linux in terms of hardware support, and this is most true for the latest, cutting edge hardware and peripherals. If you want a close to perfect OS in terms of software availability (repository packages + all the source packages available for Linux in general + pre-installed Wine for running Windows software), hardware support (drivers are built in the Kernel and so is the same for all Linux distros), being open source and also one that has the highest standards for security, I would suggest Kali Linux (previously BackTrack Linux) without a second thought. Kali Linux is the benchmark for security oriented Linux distributions and is the most popular penetration testing system in the world (hackers would know what it means). But setting it up as a Desktop system, or more specifically, as a Perfect Desktop system, would require guidance, at least for beginners. So it would be really, really interesting if someone comes up with a The Perfect Desktop Kali Linux guide.