Expression Web 2 says it can preview .php files without installing any other web server programs using it's built in development server...I found different php installation directions and expression web 2 setup here (http://www.microsoft.com/expression/news-press/newsletter/2008-04/Article01.aspx) that I'm going to try to use tonight when I get home...hope this works without any issues with my OS being 64bit!
Here's a little snippet from the link above:
PHP Development Server
We definitely saved the best feature for last. Expression Web 1 allowed you to test your ASP.NET pages out of the box through the ASP.NET Development Server. Expression Web 2 gives you the same capability for PHP pages. What this means in layman’s terms is that you don’t need to upload your PHP script to your web server and then hit it through a web browser every time you want to test a change. In fact, you don’t even need to set up a web server, e.g. IIS or Apache, on your development machine. All you need to do is download and unpack the PHP runtime and point Expression Web 2 at it (don’t worry, we’ll tell you exactly how) and you’re ready to go.