My answer to that question is pretty much the same: Apps. In my case, mostly games, but also some audio and image editing packages.

But the more I think about my experiences with various Linux distros, the more I realize that part of what I prefer about windows is its "feel". I just like the way the Windows GUI "feels". There's something about the way the mouse and keyboard respond to my input that I prefer. It's probably just that I'm used to Windows, and I could just as easily get used to Linux given enough time.

I can't really give any concrete examples, but it's got to do with the way the mouse pointer moves, the way the GUI elements (buttons, checkboxes, etc) respond, and the way it feels to navigate the GUI. Something about Windows gives me a more solid feel, whereas when I'm in one of the Linux distros, I feel like I have to carefully move my mouse and be more precise with my clicks and drags. Almost as if the hotspot pixel in the mouse pointer cursor is in the wrong place in Linux and I have to adjust my behavior to compensate. Especially when doing things like dragging window borders or navigating menus and lists.

Mac OS X is almost as bad in this regard, although I'm starting to get used to the way a Mac feels and I can sort of get around without feeling like I'm about to fall off a cliff. But there are still moments when I feel like "dammit, I clicked on that checkbox, why didn't it check?!"