I have worked extensively in developing web applications using PHP and ASP.NET, but one of the questions that I'm constantly asked by customers is whether to move forward with a php website or an asp.net website.

So naturally the first thing that comes to mind is to answer the question like this:

PHP is open-source and ASP.NET is from Microsoft.

Usually after something like that is said the customer has a blank look on there face. Apparently the fact that one is open source and the other isn't doesn't really faze them. And for good reason, because when I first heard it, it really doesn't tell me much.

I know from working with both that each have their + and - when it comes to developing websites.

NOTE: THIS QUESTION IS NOT TO QUESTION WHICH IS BETTER TO DEVELOP WITH. THIS QUESTION IS INTENDED TO BE OBJECTIVE.

My question is what are differences between ASP.NET and PHP as far as

1. Features
2. Security
3. Extendability
4. Frameworks
5. Average Development Time

And when one is generally used over the other for certain types of projects.

I am trying to compile a list of facts to be able to compare with the customer what developement platform is better for there particular project. I have done a simple search on google and a ton of articles come up, but the problem is the majority are usually biased towards PHP or ASP.NET.

Also if you can maybe provide examples from experience when one technology was more preferable than the other that would be awesome.