First of all, here is the most important: WE DON'T NEED to compile anything to get curl worked. All the extensions that we need are already in the PHP 4.2.3 zip. So here are the instructions and links to get Apache + PHP + CURL work properly:
To add cURL extension, YOU DON'T NEED to compile anything.
All the extensions that you need are in the C:\php\extensions folder. To add cURL or any other extensions:
=> Have the libeay32.dll and ssleay32.dll in the system32 folder (already done if you installed PHP)
=> Copy all dlls from php/dll/ folder to winnt/system32/ (libeay32.dll and ssleay32.dll are already there if you followed
the previous steps)
=> Remove the ";" in front of extension=php_curl.dll in php.ini.
Those instructions come from: http://www.php.net/manual/en/install.windows.php
And it should work, just test it with curl functions into your php script.