I use Windows for roughly the same reason as most people do; The fact that it came with my PC as the base system. Annoyingly, I have to find alternative tools to do things that I am able to do by default in a more configurable system like Ubuntu.}
To most people Windows isn't an inconvenience, but the fact is that Windows costs more in terms of RAM, money and processor speeds. As if the system isn't bad enough on your system resources, you can add an antivirus suite to that which also costs more in terms of both performance and money.}
From a development perspective, Windows requires additional configuration and tools that come pre-installed on alternate systems like Ubuntu. Specifically, Windows does not have a ssh client out the box and lacks tools like The Gimp which seem to function better on Unixes. Windows is also annoying to the developer in terms of performance, scripting and tools that cost a fortune.}
Luckily there are growing ways to free yourself from Windows and alternate systems like Ubuntu keep improving their software and there are a growing number of tools that help like VirtualBox and tools that work on various systems like Netbeans, IDEA, Eclipse and The Gimp to name a few.}
Most likely the main benefit in using Windows is the lack of support of software suites from companies like Adobe, and Sony, to name a few.}
Sometimes Windows has it's benefits though to people who like software like Photoshop and Camtasia. I myself like MS Office and Camtasia, but they are replaceable by Unix alternatives and these just add to the existing cost of an antivirus suite, Operating System, Integrated Development Environment and screen recorder and a good enough system to run this all on.}
It's clear that using Windows isn't really a "choice" but is a "must". It's uneconomical at times and a security risk historically. Below you can find tutorials and links in the "Links" section to tools and tutorials that may help you break away from this system.}
Finally, to the every day regular user, a Unix system may add a "new life" to an outdated computer by the simple fact that Linux systems require very little to do tasks like surfing, reading mail and document editing in a secure environment. So you may not need a new computer, but simply a new free system and a little time to get to know it.}