tyler79,
Usually in OS wars there's no definitive answer and neither is there one for the best web hosting OS category. However we can safely make some general rules of thumb. First of all Windows based servers are the way to go for ColdFusion, ASP and ASP.NET. There's really no viable options. The Open Source implementation of ASP for Linux doesn't and can never match ASP on Windows, simply because it's less performing, less stable and more buggy on *NIX servers. Why? ASP was never meant for anything else than *NIX. Very plain and simple answer.
If you however look for a mature and the most used OS platform for web hosting, don't look in the direction of Windows, but instead look at the Free Software alternatives. Mainly Linux and BSD, all being derivated from UNIX. First of all most free server software is at least available for them and run native on them, where as any ports to Windows are insecure, unstable or just not up-to-date in many cases. Or then there's no such port. I looked at your website and I honestly speaking need to criticise you abit. No, not bashing you. First of all running all especially Perl on Windows is not good for a hosting business production environment, because the ActiveState Perl distribution isn't exactly something I've found to be reliable. It's much more easier to get it running on *NIX. Furthermore getting *NIX runtime libraries needed for many scripts is not that easy, at times impossible, not to mention getting more Perl modules isn't easy either. PHP is an another story, because it has been developed with a native Windows port.
If one still wants to go with Windows, I advice to sticking to as Windows native software as possible (mainly IIS, FrontPage extensions, MS SQL, ASP and ASP.NET). Possibly PHP and MySQL as a small help for making the hosting more versatile. However you can exclude these, if you customer niche doesn't mind them. Also pay attention to the fact a Windows server may need commercial paid server applications for example your e-mail needs, in order to match the offerings of a similar *NIX server.
In the end I think this pretty much comes down to this: If you're used to Windows on your desktop and don't want to learn something new (or don't have the time), but still want the server unmanaged and run by yourself, you probably take Windows, despite *NIX would have been the better choice most likely. If you don't want to learn Linux or BSD (= *NIX) or you lack time, I recommend going managed or hiring a freelance sys admin.
