1. What % use windows?
1.1. Above 80%
1.1.1. Pros
1.1.1.1. Extended battery life.
1.1.1.2. Improved taskbar.
1.1.1.3. Windows Live, Internet Explorer 8, and new ways to work with window.
1.1.2. Cons
1.1.2.1. No more Quick Launch Toolbar.
1.1.2.2. No more small icons for the taskbar?
1.1.2.3. It is still quite possible that the Run menu item is still gone from the Start menu.
2. Linux: Open Source free
2.1. Pros
2.1.1. Everything is free.
2.1.2. Way more secure than Windows XP and even OSX.
2.1.3. More options than any other system.
2.2. Cons
2.2.1. The latest and greatest hardware is typically slower to reach Linux.
2.2.2. Limited vendor support.
2.2.3. Limited support for proprietary applications.
3. Apple: Osx, Leopard
3.1. Pros
3.1.1. Easier to use for the non technical.
3.1.2. Almost no spyware or virus applications.
3.1.3. You have almost complete access to the enormous library of free open source applications.
3.2. Cons
3.2.1. Less support. You have to goto Apple for all your hardware problems.
3.2.2. Less hardware choices than Windows. For your average user this isn’t much of a problem. All the common hardware types will work.
3.2.3. More expensive upfront than other choices. Some would say this is offset by less maintenance required over the life of the system.