Microsoft SharePoint 2010 Unleashed

Set the Default Open Behavior for Site Collections in Central Administration

This following method is also available for setting preferences for how documents are handled in document libraries:

1. From Central Administration, click Site Actions, and then from the drop-down menu, click Site Settings.
2. On the Site Settings page, in the Site Collection Administration section, click Site Collection Features.
3. On the Features page, scroll down to locate the Open Documents in Client Applications by Default feature, click Activate to open documents in the client application by default, or click Deactivate to open documents in the browser by default.
4. Test that viewing Word, Excel, PowerPoint, and OneNote documents in the browser and editing in the browser ...