In the late 1990s, you could get away with a flat Web page that displayed nothing but text. Today, a successful Web site needs to be able to interact with visitors -- to collect information and provide customisations. The way you do it is through scripting. By default, Windows 2000 and IIS 5.0 produce scripts using ASP. However, one of the hottest new types of HTTP scripting is PHP. Unfortunately, Internet Information Server 5 doesn't natively support PHP. In this article, I'll show you how to download, install, and configure PHP to run on IIS 5.0. Why PHP?
If you've previously used ASP as a scripting language, you may wonder why you should even bother switching to PHP. But there are plenty of reasons to choose PHP over ASP. For starters, PHP scripts tend to run much more quickly than comparable ASP scripts. Another reason for switching to PHP is that there are no hidden costs. In an ASP environment, if you need code for things like encryption or e-mail management, you often must buy third-party modules. However, many of the commonly used modules that don't come with ASP are included with PHP. And if you need a module of code that isn't included, there's a good chance that you'll be able to download it for free from one of the many PHP Web sites. PHP also tends to be an easy transition. PHP scripts are sort of like a combination of ASP and C++. What's more, PHP is object oriented and has a much better memory management model than ASP. This means that PHP code typically scales better for use in large enterprise applications. Essentially, PHP can do anything that a CGI script can do, but usually more quickly and efficiently. PHP works well for tasks such as collecting form data, generating dynamic page content, and sending and receiving cookies. Installing PHP
The first step to installing PHP support is to download the PHP source files. As of this writing, the most current version is PHP 4.2.2. (Editor's note: At the time of publication, version 4.3.0 had recently been released.) You can download the PHP files from the PHP Web site. All of the necessary files are included in a 5-MB Zip file. You also need to download an installer, which is contained in a separate 913-KB Zip file. A lot of files are available on the PHP Downloads site, and figuring out which files to download can be confusing. Figure A shows you the two files you need.

Figure A

These are the two files that you need to download.

Begin the process by downloading the PHP source files and unzipping them. When you unzip the archive, be certain to extract the files using the Original Path option. Otherwise, many of the files will be placed in the wrong directory, and the installation process won't work. When decompressed, the source files will consume about 13 MB of disk space. Once you've downloaded and decompressed the PHP source files, download the installer program. The installer is contained within a file named Php-4.4.4-installer.exe. It automates the installation process for the CGI version of PHP. Before you begin the installation process, you should know that the installer doesn't install any extensions or server API versions of PHP. And although PHP 4 comes with several SAPI modules, they're very buggy and aren't recommended for use on production servers. Therefore, I'll focus on installing the CGI version.