The following hint will apply to anyone who wishes to use a default language in Office 2004 for the Mac [e.g. English (UK)], and that language is not the selected default Mac OS language (e.g. Irish settings and Keyboard layout). It took a lot of fustration and a long time to find out why I could not get Word 2004 to spell check newly created documents without manual intervention, and the following is an explanation of and a solution for the problem (if you open existing Word documents created in previous version of Office, the spell checker works flawlessly). Hopefully Micrsoft will be able to provide a better and more appropriate language solution in time.
It appears that under MS Office 2004 for the Mac, Microsoft has changed the way the language settings within Office are set/recognised. Up until this version of Office, the language was set within Office itself. However, as of Office 2004 for the Mac, it gets the default language setting from the International Control Panel in System Preferences. (The latter is key to resolving the problem.)
For example, I live in Ireland and for no reason other than aesthetics, I would prefer to use the Irish keyboard layout with the Irish flag rather than the British keyboard layout and the Union Jack. However, I cannot do that and have forground or background spell checking of any new document created in Word 2004. In fact, if I set my system up using all-Irish settings (even the English version of the Irish settings where available) in the International Control Panel, I will not be able to set English (UK) as the default language in Office 2004, nor have English (UK) spell checking by default in any new document I create. If I use the Irish settings, I can set English (UK) as the default language and use the spell checker, but only on a per-document basis. So far, I have been unable find out how to do it automatically. For obvious, reasons this isn't practical..
If I as an Irish user want to be able to create a new Word 2004 for Mac document, and have it auto spell check using English (UK) as my default language, I have to accept the following settings:
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050204083233639