Linux is valued as a high performing operating system. Due to its
modular nature - entire portions of the operating system can be
easily added or removed, the operating system can be easily tuned
for a specific purpose. Need a webserver? You can install a
webserver only system, no gui, no nothing you don't really need.
"Need a mailserver? You can run a dedicated mailserver without a
problem, just doing mail and nothing else.
Linux is more stable than windows. Does your boss ever get
frustrated with windows because of the instability? Tell him/her
about Linux stability, and how it's almost always possible to
recover if something "hangs" in Linux. In windows if something goes
wrong the whole system freezes and you can only fix it by
rebooting. This almost never happens in Linux, if something goes
wrong a program may freeze and you can easily kill of that