WSS does not support multi-language sites out of the box, you would need MOSS for that (the feature is called 'variations'). You could create a site for each language you want to support and then use redirects to send users to the correct site. There is probably a way to "activate" the multi-language features thru custom code (like the auditing behavior), but I am not aware of anything off hand for that.
You cant change a sites language settings after it is deployed as it is part of the site template. There are tricks like backing up the site and editing the template files and redeploying the site, but this will only net you the single language change, not multiple languages for the same content.
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