I don't, or actually I don't use it as my primary work computer. I do enjoy *playing* with Linux though and feel it has some aspects which are superior to Windows. Windows also has some great features, but it's not a black and white world. There are things I enjoy and dislike about each OS. Here is a list of some of the things I like about Linux I think Windows could stand to borrow.
I really like how customizable Gnome and Kde are. I mostly stick with Gnome, but I believe this applys to Kde as well. You can load new visual themes in Linux that not only change the way widgets are drawn, but also change a lot of the system metrics, and also replace most all of the standard icons used by programs system wide.
On the topic of icons, I think it's a really great idea to allow the OS to hold the icon theme for your application. I know Windows has image lists, and of course there is the shell image list, but those are either geared towards your own private images, or images related to the shell and not common action images (such as copy, cut, paste, play, stop, etc).
Another tidbit about Linux icons, they tend to be pngs (with an alpha channel) and also scalable (svg). Sure Windows now has IImageList to support 32bpp images, but it would be nice if ImageList also supported both raster and scalable image formats.
While themes were greatly appreciated with Windows, it's never been satifactorily explained to me why Microsoft choose to lock down the theme system so that only they could provide the theme files. My guess has been Microsoft did this to protect themselves from allowing people to skin their OS to look like their next version. After all, a big criticism of each OS they put out is that it is little beyond the old OS, but with a new layer of gloss. If people could easily and safely download and install new skins, Microsoft's would be giving people even less incentive to upgrade.
In my opinion, again Linux gets hardware compositing through Compiz done right, or at least it's better than Windows. This point is related to the last in that the desktop compositing is open to customization. I see a lot of interesting and useful plugins brought into the mix by individuals, whereas in I haven't seen any third party making interesting use of the Windows compositing pipeline.
Here are some of the Linux Compiz plugins I really think add to the UX: Desktop zoom, desktop lock, switch desktop, move window to another desktop, scale window to screen, arrange windows to grid, etc
I also like how I can easily bind my own keys to system functions including keys to initiate the above commands.
Application and Library Repository
It's quite refreshing to be able to type "apt-get install monodevelop", or to launch the add programs dialog and search through a lot of community rated software.
Organization and Security
I like the way organization and security work in Linux more than UAC. I have my own home folder, and everything specific to me is palced above that. I can install apps to a folder off my home directory, or place downloads in a folder off my desktop. I don't have a lot of nutty folders of my root folder like both "My Documents" and "Documents". The whole "My" prefix was silly to begin with. Also, since the names of folders are based off your login name, you don't have to fiddle with dealing with the locatization of special folder names.
Speed and Memory Usage
My Linux system can run with 256MB of ram and still run ultra smooth with all the effects on, with absolutely delays related no page swapping. The overhead of Linux is quite small not like with Windows. I can encode an MP4 using HandBrake, have two PDFs open, browse with Firefox, and still have memory and CPU cycles left over.