For GD dlls, try:
http://php.weblogs.com/php_gd
or
http://php4win.de/
Note: Most Win php bundles (4.03; 4.04) come with php_gd.dll already included. Look in the ..php/extensions directory to verify that.
To enable GD, your php.ini must include the lines: extension=php_gd.dll and extension=php_zlib.dll (usually you need only to uncomment, i.e, remove the ";" from in front of those two extension listings, if they are already written there).
Second, make sure the extensions directory path listing in your php.ini (extension_dir=) is correct.
(Example: Gumby needed to change extension_dir= ./ to extension_dir= c:/gumby/php/extensions)
If php_GD.dll is inside your php/extensions directory, and is correctly addressed and uncommented inside php.ini, then your phpinfo page should show GD as "enabled".