All clients assume everything is run in Linux. I don't even know why this mindset is so popular.
When we develop something and the client wants to host it I can guarantee (more or less) that the platform is Linux and they want to know why the software we have written doesn't work on Linux.
I know there is Mono but I always use IIS to run our software as that's what I am used to and that is the platform is is meant to work on.
I do love .NET, I've used it since it was launched. I do want to have a change though. I just don't know what language to dip into next.
I'll never leave .NET though as it's where I really started programming (after VBA...). I've just discovered Umbraco too which I've just fallen in love with.
Recommendations on languages I can try would be appreciated. I don't like this minefield we are in at the minute, I never know what is going to stick around and what is a fad.