For twelve years now I’ve used Linux as my primary desktop operating system. I can’t imagine using any other operating system on my computer. Here’s why:

• It’s totally free with easy updates via apt-get. Distribution upgrades sometimes requires a bit of tweaking of files but are relatively easy to use. No fancy installers that block what you are doing or lots of windows to click through.
• Software all comes through the apt-get mechanism, you don’t have to go to risky websites to download software.
• Standard Unix programs and functions are easy to script in bash and pipe their output between processes.
• Most things nowadays are done on the web and the Linux web browsers are in most ways the same as the commercial platforms.
• OpenOffice is a fully functional and stable office platform for all my office software needs.
• QGIS as somebody who enjoys mapping and exploring land has become a killer geographic information system, especially in recent years. It takes full advantage of the GRASS platform and various Unix based GIS software.
• Great professional web development tools that are running in their native environment
• I am not a fan of overly glossy things, so I use the fast and simple XCFE desktop environment which is great because it never changes. Even Linux itself pretty much stays the same, although little things evolve over the years.