Gnope has proven to be the most easiest way of installing and maintaining PHP-GTK 2 on Windows. Gnope is a fully featured PHP-GTK 2 installer, complete with PHP 5.1, GTK 2.6 and PEAR. A few simple mouse clicks and you're done!
Just download the installer from gnope.org and follow the on-screen instructions. Gnope also has a PEARified channel of its own, where you can download PHP-GTK 2 applications, in addition to official PEAR packages, e.g. from the Gtk2 category.
Download the Alpha binary release of PHP-GTK 2 for Windows from the PHP-GTK 2 download page. Unzip the file into a directory of your choice. A directory named php-gtk will be created containing everything included in the release.
You will need a copy of php.exe (CLI Version) and php5ts.dll, both of which are available in the binary release of PHP 5 for windows, and put them in the php-gtk directory. If you wish to use any other extensions with this copy of php.exe, make sure you put their binaries here too.
After this, you must set your PATH variable to include the gtk+2.6.9 directory present in the release. You can also let the gtkpath.bat batch file set the appropriate PATH for the current command line session by executing it.