VISTA have built in RMS client.

RMS topic was dedicated to help solve my friend, Syahrul's problem. Below article was taken from Microsoft as refer by him.


Rights Management Services

To facilitate sharing and collaboration, the Rights Management Services (RMS) client is now part of Windows Vista. RMS is designed to secure data against unauthorized use when it is sent in e-mail or used in any other rights-enabled application, such as Microsoft Word or Microsoft Excel^®. There are three components to the RMS solution: the server, the desktop, and the platform. For the server part of this equation, Windows Rights Management Services for Windows Server™ 2003 is required. This information protection service of Windows Server 2003 establishes user account certificates, issues use licenses, enables the creation and storage of the rights policy templates, and so on.

The desktop tier performs the actual data security operations like encrypting data, and is planned for inclusion by default on Windows Vista. This allows you to use applications that integrate with RMS technologies and immediately take advantage of the feature without incurring the cost of an additional deployment.

Windows Vista also provides a significant update in the RMS platform for creating rights-protected information. This update comes in the form of Windows Presentation Foundation, which delivers a set of APIs that allows developers to rights-enable any file built using the Open Packaging Conventions. This defines a file format for application information that will be used by XML Paper Specification (XPS) Documents and the next version of Office. Windows Vista will also include an RMS-enabled XPS Viewer that can rights-protect any data published in this format.