OpenOffice is an open source project, based on Star Office which was a project started by Sun Microsystems. OpenOffice is a complete office suite with word processor, spreadsheet, database, presentation (powerpoint type) and drawing package. The software is free and there is an active community of users to provide help and support. Open office can open documents created in Microsoft Office and you can save any documents you create in Microsoft Office format and many other formats so sharing files with friends and colleagues is easy. It is the only office application that I have on my own computers.
Mozilla Thunderbird is an alternative to Microsoft Outlook. This is a fully featured application with anti phishing settings and the ability to block images in e-mails, amongst other things. Manage multiple e-mail accounts with ease and rely on the spam filtering options to allow you to control what arrives in your mail box, again this is the only e-mail client I have on my own computers.