If your php directory is NOT in your path - add it. This makes EVERYTHING a LOT easier.
RIght click "My Computer" and choose Properties|Advanced|Environment Variables|System Variables|Path|Edit
I use PHP a LOT!!!!, so my path is ...
C:\BATCH;C:\PHP5;C:\PEAR;C:\Program Files\WinRAR;C:\PKWare;D:\SAGE\UTILS;C:\Program Files\Microsoft SQL Server\80\Tools\BINN;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;D:\Data\Web Sites\Quick Scripts\public_html;C:\Program Files\Support Tools\;C:\Program Files\Windows Resource Kits\Tools\;D:\cygwin\bin;C:\Essbase\bin;C:\Program Files\Intel\DMIX;D:\Program Files\InVu\;C:\Program Files\QuickTime\QTSystem\
I have C:\PHP5 near the front of the path. Just do. You don't need to if you just want to add it to the end.
Having saved that open a cmd prompt.
Type PATH [enter] just to make sure PHP is in the path.
If you are using a different directory then make sure you add that directory!
At the cmd prompt type
C:\>php -i | find "Configuration File" [enter]
This will return something like ...
Configuration File (php.ini) Path => C:\WINDOWS\php-cli.ini
The file (C:\window\php-cli.ini) could be anywhere/anything.
Edit that file and check that extension=php_curl.dll has no ; in front of it.
Save file.
Back at the cmd prompt type
C:\>php -m [enter]
You will get back something like ...
[PHP Modules]
bcmath
calendar
com_dotnet
ctype
curl
date
dom
ftp
gd
hash
iconv
libxml
mhash
mssql
odbc
pcre
Reflection
session
SimpleXML
SPL
standard
tidy
tokenizer
wddx
xml
xmlreader
xmlrpc
xmlwriter
xsl
zlib
[Zend Modules]
Zend Extension Manager
The actual list will depend upon your settings.
If you see curl there, then PHP managed to load the curl library and the functions are available.
If you get ANY error or CURL is not present, then let me know.
This is working, so far, at the cli version of windows.
Now create a file called info.php containing
<?php phpinfo(); ?>
And save that in your webroot somewhere.
Open your browser and open the info.php
Look for "Configuration File" and curl. See if the same config file is used (I use different ones for CLI/FCGI/CGI/ISAPI).
If you are using the same config file and curl is NOT present, restart your web server. Then recheck.
At this stage, any errors would be important.
Let me know.