Just convert your default document types to Word, Excel, etc. 99% of OOo users do that.
See here:
Configure, Change or Set OpenOffice.org to Default Save Files in Microsoft Office Formats
http://www.mydigitallife.info/2007/01/25/configure-change-or-set-openofficeorg-to-default-save-files-in-microsoft-office-formats/
There was also that option when you installed OOo.