If you are running OpenOffice.org and Firefox at the same time you can view OpenDocument and other OpenOffice.org supported file formats using the provided Mozilla plug-in.
First you need to activate the plugin. To do so, in OpenOffice.org, select Options…in the Tools menu. Expand the Internet item, select Mozilla Plug-in and check Enable.
You’re ready. OpenOffice.org will now register the document extensions it can handle and Firefox will use the plugin to display them, as shown in the screenshot below.
Along with the content, you can perform basic operations like save the document in any of OpenOffice.org supported formats including Microsoft Office and PDF, send it by email, open it in OpenOffice.org for full edit options, zoom it in or out, print or navigate it.