It depends. If you are running a very old version of Windows XP, then no. The computer would be too old to be compaitable with a newer version of Microsoft Office. For sure, if you have Windows...
In my opinion, Microsoft Office is too expensive for what it is. When you buy Microsoft Office, you are paying for the brand name. Open Office is free and simply looks less fancy than MS Office, but...
The Office button in PowerPoint 2007 (and all Microsoft Office products) is found in the top left corner of the presentation window once it is opened (see the image to the right).