Open Office is not Microsoft Office. Open Office is an office suite that is comperable to and compatible with Microsoft Office. Open Office is compatible with .doc documents, but so is every word processor/text editor out there now. TextEdit handles .doc just fine.
Downloadable PowerPoint? Demo from MS, sure. OpenOffice has a presentation app.
OpenOffice is great, by the way. In Windows and Linux it's fantastic. When it runs natively in OS X I'll happily use it instead of AppleWorks.