- Some MS Office documents aren't displayed right with OpenOffice. There are few ones, but it still happens.
- Documents with Macros often aren't handled.
- You just don't want to start OpenOffice to see a PowerPoint that a friend has send you via email, because it isn't immediately.
You don't have to.
There exist free tools from Microsoft which can display Word, Excel and Powerpoint documents, without having installed the Office Suite.
Moreover, they work perfectly with Wine on Linux.
They are simple Viewers, you can't edit the documents, but printing works as well.
You can find them here: