Microsoft Office is a fine product and is used by millions of users to create spreadsheets, manage email, write letters and create Powerpoint presentations. However, with all that functionality comes a hefty price tag and there are many alternatives to MS Office. For years, I have used OpenOffice, one of the best open source and free solutions with full integration and compatibility with MS Office. So, you can create a document in OpenOffice and someone on the other end of the globe can open it in MS Word.
Available on all platforms including PC and Mac, it is the best open-source office solution for word processing, spreadsheets, presentations, graphics, databases and more. Free to download and use, I highly recommend it. The only thing lacking is an open source solution that is comparable to Outlook but you can always use one of the free mail clients like Thunderbird, IncrediMail or Mail. For a complete list of features and learn more about it, follow this link: http://why.openoffice.org/