http://en.wikipedia.org/wiki/StartCom

Free Clas 1 (personal) SSL Certificates.

Trustedness In contrast to CAcert.org, which also offers free Class 1 SSL certificates, the StartSSL certificate is included by default in Mozilla Firefox 2.x and higher, in Apple Mac OS X since version 10.5 (Leopard), all Microsoft operating systems since 24 September 2009,[2][3] and Opera since 27 July 2010.[4] Since Google Chrome, Apple Safari and the Internet Explorer use the certificate store of the operating system, all major browsers include support for StartSSL certificates.

https://cert.startcom.org/

Get Your Certificate:

From: http://support.godaddy.com/help/article/4875/installing-an-ssl-certificate-in-microsoft-iis-5-amp-6

Installing an SSL Certificate in Microsoft IIS 5 & 6

You must install the intermediate and primary certificates to your Microsoft® IIS 6 Web server to complete installation.