Currently Being ModeratedSep 3, 2012 7:02 PM (in response to SusyC15)
Before you start, make sure you backup all your data and files... you know, just in case.
Then follow the instructions in the software package, whether it be for upgrading from a previous version, or uninstalling the previous version and installing the current version.
That's the best advice anyone can give you. It's like 6 of one, or a 1/2 dozen of the other.
Currently Being ModeratedSep 4, 2012 6:16 AM (in response to SusyC15)
I've recently helped someone upgrade from Office 2004 to Office 2011. (I also have Office 2011 Home & Business installed, alongside Office 2008, but I no longer have earlier versions installed.)
You can install multiple versions of Microsoft Office and use whichever one you like. They end up in different folders inside Applications, e.g. "Microsoft Office 2004" and "Microsoft Office 2011". When you set up Office 2011, it offers to import data from older versions (e.g. to get Entourage e-mail and accounts into Outlook), and inherit details like your name.
By default, the system will normally launch the newer version of the application when you open a document, e.g. Word 2011 if you double-click a ".doc" or ".docx" file.
If the older version (Word 2004) was already running and you double-clicked a ".doc" file, it would open in Word 2004. Word 2004 doesn't directly support ".docx" files but can do so via the OpenXML converter, so I'm not sure what would happen if you had that installed and double clicked a .docx file while Word 2004 was open. It might convert and open the document in Word 2004, or launch Word 2011.
At a later stage you can uninstall Office 2004 without affecting Office 2011, but you might need to do some manual cleanup to tidy up old Office 2004 identities (which live in the Microsoft User Data folder in your Documents folder).