Whether or not you need the Business Edition (it's mainly relevant to people using Entourage with Exchange), you can still benefit from some free lynda.com videos that are available on Microsoft's Mactopia web site.
The 25 videos cover the Office 2008 versions of Word, Excel, Entourage and PowerPoint, including common tools such as WordArt and charts.
Specific topics include Word's publishing and notebook layouts, configuring POP and IMAP settings in Entourage, creating new presentations in PowerPoint, and saving workbooks in Excel.
There is some overlap between the Business Edition videos and those provided through Mactopia.
lynda.com also offers a free seven-day trial of its complete Office 2008 training library.