Windows isn’t just for games. There are hundreds to thousands of appliations that run on Windows, but neither run cleanly on Linux nor have a direct Linux port.
Mobile Sync software is an obvious biggie (iTunes, Windows Media Player, Zune, Mobile Device Center/ActiveSync, BlackBerry Desktop Software). Microsoft Office. People who Develop for Windows, do Video or Graphics Editing, high end Desktop Publishing, Sound/Music Editing. The list goes on. These are done on UNIX systems as well. I’ve seen lots of Solaris workstations doing some rather high end stuff (Workstation Graphics drivers are usually available for Solaris - Quadro and FireGL). HP-UX as well. You can never “miss” those CDE/Motif interfaces…
The Applications that many people list in rebuttals are merely alternatives. They aren’t replacements. Evolution and Thunderbird can’t replace outlook for me. They can’t replace Outlook for me connecting to Windows Live, how are they gonna replace Outlook connecting to Exchange.
If you don’t do any work on your computer (Windows is just for gaming!!!), then sure… You don’t need it.
But there is a reason why Linux has such a terrible marketshare on the desktop (they tried with Linux Netbooks and Laptops, that was a failure). Applications matter, and doing whatever it takes to limit people to F/OSS software or running (or trying to run) their Windows software in a Compatibility Layer (like WINE) won’t help that. Consumers don’t like to run multiple operating systems in VMs. That’s common with Power Users and Developrs, but Power Users and Developers are a significant minority of computer users.
Even if every Linux User and Software Developer did that, it would still be factorably less than 10% of the market (cause Linux only has like … 2% marketshare, or something not much more than that…).
As far as Gaming goes, it’s Linux’s fault that they have no decent titles for the platform. The Kernel Developers intentionally refuse to keep the Driver API/ABIs stable. Gamers don’t like it when an update breaks their driver and puts them out of commission. It doesn’t happen on Windows or MacOS, so they stay there.
Back in 2001-2003 there was a lot of effort to port lots of games to Linux (mainly driven by Loki). No one wanted to listen. Now, companies will just port to MacOS. In the future, they may port to Solaris if the user base grows enough and Hardware support improves, since that OS is backward and forward-compatible (and has been for almost a decade), unlike Linux.