Running PHP in Visual Studio 2010 doesn't open the php file in the browser

I have a Wordpress project that I'm developing in VS2010 (with VS.Php). When I try run tone of the php pages in the browser, I get a alert that asks how I want to open the page, or if I want to save it:

I've configured my local IIS (Windows XP, IIS 5.1) to open php files, but VS d开发者_StackOverflowoesn't use local IIS to run projects. How can I configure IIS express that runs the VS project, to open php files?

I see that it's because the project in VS is not a PHP project.
The way I created this project was by using Webmatrix. I created a Wordpress site in Webmatrix, and when I clicked the Launch in Visual Studio button, it created a project in Visual Studio. But apparently the solution that was created was an ASP.NET one...
After that, I tried creating a normal PHP project (enabled by VS.php), and then PHP worked perfectly.