I think Hoverman was saying that Publisher in Office XP is different to MS Publisher - it isn't. I've got Office XP Pro and MS Publisher.
From MS Publisher help
File types that Publisher will open Microsoft Publisher can open the following file types:
Microsoft Publisher versions 98 and later Microsoft Word 2.0 and later Microsoft Word for the Macintosh 4.0?5.1 Microsoft Excel HTML Lotus 1-2-3 Plain (ASCII) text Rich Text Format (.rtf) Unicode text WordPerfect 5.x and 6.x