I am using Linux for more than 8 years now, mostly for the desktop, but also as LAN server. On my laptop, I only use windows for Orbiter, and for compiling and testing the windows versions of the software I make (which is all multi-platform and also compiles in Linux). Overall, I spend more than 90% of my time in Linux.
I started using Linux about a year before desktop environments like KDE and Gnome appeared, and in those days it really deserved its "nerds-only" image. Because I didn't just give up, I now have a more-than-average "under-the-hood" knowledge of Linux. I still use the commandline a lot for fixing some of the problems you always have when installing a new system. Maybe that's why I continue to like Linux, while others don't manage to fix their problems, and go back to windows.
My experience is that Linux is a perfect system as soon as it is installed and configured properly. Distributors like Ubuntu do a very good job in easy installation and configuration, but with thousands of different pieces of hardware on the market, it's nearly impossible to make it work for everybody. Things would improve a lot if hardware vendors would start pre-installing Linux on their computers, just like they are now pre-installing windows. They know their hardware, and they have the experts who can configure Linux properly, so that you don't need to be a geek like me to appreciate Linux.
I tried Orbiter in wine, but it doesn't work for me. I am using Xubuntu 8.04, and I am getting a DirectX7 stub error, and no 3D rendering.