Our Servers uses Unix based operating systems because of the superior performance, flexibility and cost efficiency that Unix offers.

The following is a comparison of the BSDI system to the Windows Server system.

Note: The operating system that you use on your desktop computer (the vast majority of people use some flavor of Windows) has absolutely nothing to do with the one that your host needs to serve your web site.
Most personal sites are created with MS FrontPage and even although that is a Microsoft product, it can be hosted perfectly on a UNIX web server with FrontPage Extensions installed.

Performance
When tested with Unix and Windows running on standard PC Unix ran 27% faster than Windows when reading static HTML content, and with API generated content.
Unix is between 47% and 197% faster. For CGI, PHP and MySQL contents Unix is approximately 77% faster than Windows

Reliability
Individuals and subsystems running on Windows crash far more frequently than a Unix system.
Unix has been reliable for years due to its dependable software and technology.

Efficiency
Unix offers more performance at 1000MB than Windows offers at 2000MB.
Unix is usually more proficient in the use of its memory, especially when dealing with network services Because Unix requires less memory and processor time than Windows, a Unix based system has more memory and processor power for other computer functions.

Remote Management
Unix was designed and implemented with remote management in mind.
This enables system administrators to remotely perform management operations from another building or across the world.
Windows was designed so that most of the administrative programs have to be run on the physical machine, without the ability to remotely control the machine.

Internet Services
Unix has included things such as SMTP (Email), NNTP (News), Telnet, and DNS.
All of these protocols and services were somehow forgotten by Windows.
They can be covered up with third party products and Microsoft's own programs. However, none of these programs and products can compare to Unix in terms of flexibility and power.

Stability
UNIX systems are hands-down the winner in this category.
There are many factors here but to name just a couple of big ones.
In our experience UNIX handles high server loads better than Windows and UNIX machines seldom require reboots while Windows is constantly needing them.
Servers running on UNIX enjoy extremely high up-time and high availability/reliability.

Compatibility
Web sites designed and programmed to be served under a UNIX-based web server can easily be hosted on a Windows server, whereas the reverse is not always true.
This makes programming for UNIX the better choice.

Conclusion
To sum it up, UNIX-based hosting is more stable, performs faster and more compatible than Windows-based hosting.
You only need Windows hosting if you are going to developing in .NET or Visual Basic, or some other application that limits your choices.