For a project i needed a Windows LDAP server (client) software. I try out some commercial and freeware tools. Add the end i like Apache Directory Server the most. So if you are searching for a freeware easy to use LDAP solution for Windows checkout this product.
Apache Directory Server
ApacheDS is an embeddable directory server entirely written in Java, which has been certified LDAPv3 compatible by the Open Group. Besides LDAP it supports Kerberos 5 and the Change Password Protocol. It has been designed to introduce triggers, stored procedures, queues and views to the world of LDAP which has lacked these rich constructs.
Apache Directory Studio
The Studio is an LDAP client platform. It is composed of an Eclipse RCP Application and a set of plugins. Primarily it is built to be used with ApacheDS, but it should work with any LDAP server.