Sorry, but IIS is free (assuming you have Windows) and I'm coding .NET and MySQL as I write this. Oh, and I've never seen a server run by a proper IT admin get a virus - only people who use the server as a workstation get infected.
Splashup.com is .NET, IIS, Windows Server 2003 and MySQL. It's never crashed unless I've borked something and it's been through a Techcrunch, Lifehacker, and Digg on the same day.
The amusing part about the free tools argument is that the cost of tools is such a non-concern in the professional world. I work for large customers on large projects and tools, whether they be Microsoft, Oracle or IBM, no one's worried about that.
Then again, you might be talking about little side projects, my frame of reference is mostly multi-million dollar systems.
Even at large companies, all things being equal, having no licensing costs is a competitive advantage.
Two words: hanging chad