To convert a works doc (or any other document for that matter) right click the document, click open with...., click the document you wish to open it with. It will open. Then save it as a word...
If ur PDF files are made from Word documents, just use the Adobe PDF reader to save the PDF to Word file directly. In addition, if the PDF are image-based, you need a OCR software to assist you.
Powerpoint files can be opened in the Open Office Presentation section. Select a New Presentation from the File menu. Select the Open Existing Presentation option. Click the Open... button and select...