Fatal error

Hi. I am working on a website locally using Xampp. Have installed your plugin, but when I attempt to check out I get the following error:

Fatal error: Call to undefined function curl_init() in C:\xampp\htdocs\wordpress\wp-content\plugins\paypal-express-checkout\classes\paypalapi.php on line 86

Any idea what might be causing this? Thanks in advance!

http://ww.wp.xz.cn/extend/plugins/paypal-express-checkout/