Seems some people have the misconceptions Microsoft gives them. Kinda like the belief that OpenGL is only useful for scientific representations, and no good for gaming.
There is a very large amount of support for Linux machines. I remember going to a site once that showed a list of compatible games, and any game I wanted to play was there, other than Steam-based games. Yeah, that really broke my heart ([/sarcasm])...
Most companies write their engines for both Linux and Windows at the same time. Id Software, and Bioware for example. Neverwinter Nights is Linux-ready (you lose out on the videos, but, the videos aren't worth watching
), DOOM III is Linux-ready, etc.
When it comes down to performance, I always found I got better performance out of Linux, because of the way their architecture is designed. Regardless, I'm not a fan of Windows or Linux. I use Windows, and I'm not happy or unhappy with that.
The pros and cons:
Windows:
Pros-
-Takes little time to configure, and drivers are readily available for your devices.
-Designed so even an idiot can run it.
-Broader game selection.
Cons-
-Performance is hindered by lots of useless crap.
-Susceptible to viral and spyware attacks.
-Most applications for the nicer functionality cost big bucks.
Linux:
Pros-
-Almost immune to viral and spyware attacks.
-Superior architecture allows for speed improvements.
-Almost all the good software is free.
Cons-
-Only power users can truly use it effectively.
-Even updating a single device can take an hour or more of configuration, and the drivers can be hard to find.
-A smaller game selection, and the free software can sometimes be a liability because it may be lower quality.
These aren't the full monty, perse, when it comes down to pros and cons, but they're the pros and cons for a gamer user, and a simple user. Fortunately some games not natively supported can be run with WinE (Windows Emulator), however, they're not going to run as well, and if they use a Windows-based API, you're probably out of luck.