Support Desk Software for ITIL-Based IT Department

Wasteofspace asks: "At my current workplace (local government, 250 user site) we are currently working towards achieving a more structured IT department using guidelines set by ITIL. Currently we are using a very poor call logging system running on a Lotus Domino Server, that has no tracking, incident management, problem management etc, and does not integrate into our current directory services (Novell NDS, soon to be migrating to Microsoft AD). Does anyone have any suggestions on a provider of an ITIL compliant support desk application, that is reasonably easy to use, has integration into an LDAP compliant directory service, and has self service functionality for users?"