Microsoft Office 2007 Home and Student edition is a great option for word processing, and more. Most computers do not come with a word processing option, and Microsoft office comes with multiple products to suite your needs.
For just $159 you get Word, PowerPoint, Excel, and One Note. You also get licensing to put the software on 3 different computers!
Have a Mac? Try Microsoft Office 2008 for Mac. Includes Word, PowerPoint, Excel, Entourage, and MSN Messenger. Again the licensing for 3 different computers is included for just $159!