Office HTML viewer to support Users without Office
The Office HTML Viewer server provides support for users who want to view the content of files in Microsoft Windows SharePoint Services document libraries, but do not have Word, Excel, or PowerPoint from Office 97, or a newer release of Office, installed on their local computer.
This is a free download from Microsoft: http://www.microsoft.com/downloads/details.aspx?familyid=c62e0232-9bf6-48fc-829e-5c34d5c8b15f&displaylang=en
Hava a dedicate a server for the Html Viewer Server. Once you have it installed, go to Central Administration > Application Management > External Service Connections > Html Viewer and configure MOSS to use the server.
Once you enter the deatils of the URL of the HTML viewer and the check box" Allow HTML viewing"
See the figure below.
Sharepoint-HTML Viewer