I needed some SSL certs for my Exchange and other servers. I wanted to buy some certificates from an commercial supplier like godaddy.com or something like that. But this is how I’ve fixed the problem.
Go to CAcert.org (https://www.cacert.org/index.php) and register/create an account.
Create an certificate request on IIS or an server you wish to create an certificate and submit this on the site.
Only one downside, the root certificate isn’t standard know. You must manually import it, read the howto here :
Thanks for macmenco for the hint!