Following on from Richie's reply, it means you need to install your older version of Office first before upgrading to 2003. Having said that, don't try and run any earlier version than 2003 under Vista, you'll get all sorts of trouble. Simply install your old version and then immediately do the upgrade followed by a Microsoft Update.
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Do you know that we're all in line for succession to the throne? Really?
Well, if forty-eight million, two hundred thousand, seven hundred and one people died I'd be Queen.