I use Windows 7.
- the snap feature. I hate it when I have windows everywhere (when at most I have one full screen, or two side by side to reference something) - everything is so cluttered and cramped. When I have 30+ Windows open (spreadsheets, folders, IM windows, text editors, IDEs, browsers, etc) it can take forever to find the right window, especially when I'm rapidly moving back and forth between them. But with Windows 7 (and KDE, I don't know of any others), I can quickly drag the window to that side of the screen and it fills to take up that entire half.
- Microsoft OneNote.. I have a tablet PC, and I have tried to make the switch to Linux full-time on it, and run OneNote inside a virtual machine or Wine, but it's just not the same! The smooth crisp lines of the pressure-sensitive stylus that organically thin out as you release the stylus from the screen can't compare with the crappy tablet support in all of the virtual machines I've tried that draw blocky single-thickness lines that lag a second behind my hand.
- Direct3D - so I can play most mainstream games.
- NVidia 3D Vision - any Direct3D program automatically turns 3D. Sure you can purchase their professional version that support quad-buffered OpenGL programs - but you have to specifically code in support into the program - it's not automatic.
My favourite Linux distro is Arch Linux.. It has a nice package manager and build system.
I use it a lot at work when I'm working on software that uses the Unix build system. I run it inside of a VirtualBox in seamless mode, with the KDE taskbar on one screen, and the Windows taskbar on another. It's great - I can even copy and paste text and objects and even drag files between the two operating systems.
