I do notice that hosting plans with open source scripting such as PHP is much cheaper than .NET or CF. That should save me a little money per month for learning and development purposes.

What is your thought on dedicating on a specific language such as .NET, CF, or PHP and not knowing another language for future career advancement? It is great that competition among many programming languages create many features and reduces bugs, but the headache of keeping up to date with ever more languages makes me wonder which language will provide me with the greatest opportunity for career advancement. "Knowing" many languages is possible, but being an expert means full dedication to a specific programming language.