Microsoft Word can open Open Office's ODT files, Microsoft Excel can open Open Office's ODS files and Microsoft PowerPoint can open Open Office's ODP files, so you shouldn't need to copy/paste anything between Open Office and Microsoft Office for these apps. Almost everything should convert. Other Microsoft Office applications presumably have Open Office filters also.

Once you've opened an Open Office file with a Microsoft Office application, though, you should save it in the corresponding Microsoft Office application's native format (e.g. docx for Word documents, xlsx for Excel workbooks, pptx for PowerPoint presentations).

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Cheers,
Paul Edstein
[Fmr MS MVP - Word]