While install magneto it fails with message,
PHP Extension "curl" must be loaded
Cause of the problem
After the Magento release (0.6.12510) installation wizard, it is checked whether php_curl.dll extension is enabled inside php.ini file. If the extension is disabled then magneto installation fails with above message.
Solution of the problem
On your windows machine with XAMPP installed go to the apache/bin/ directory.
There you will find php.ini file. Open the file with any editing software (like notepad). Search for (CTRL+F) for curl. You will find a line like below.
which means it is commented. Comment out it i.e remove semicolon (;). In order word make it like below.
and save the file.
After save it restart you apache web server.
And then try to install the magneto. You will see it is successful.
If you use debian linux or ubuntu then you can fix the problem by,
apt-get install php5-curl