It's easy to have both IIS and Apache servers running together at the same time on your local machine. Get IIS running first. Then set up Apache to Listen on a different port (in the httpd.conf file, find the Listen directive and change it to something like this):

Listen 127.0.0.1:8080

You can also set up Apache to use the same DocumentRoot as IIS (I use c:\inetpub\wwwroot for both), so you can test scripts on both servers without having to move things around.

Use php_info() to verify the same script is called like this:

IIS serves http://localhost/test.php Apache serves http://localhost:8080/test.php