It also adds support to the Word Viewer 2003, Excel Viewer 2003, and PowerPoint Viewer 2003 to open DOCX, XSLX, and PPTX files. Once you install this pack, you don't have to do much to make it work. That means you should set aside some time to download it if you're on a slow connection. It's a surprisingly big download - checking in at 37MB. If you're still using Office 2000, Office XP, or Office 2003, then this patch will help you easily open, edit, and save files created with newer versions of Office. However, before you install this pack, make sure to download and install all of the latest updates from Microsoft. If you're using an unpatched version of Office, this download will fix it. Microsoft Office Compatibility Pack makes files created with Office 2007 and later work seamlessly on earlier versions of Office.