Integration doesn't refer to sending docs by e-mail, it is related to document management. Don't use it.
If you do, then a GroupWise dialog, rather than the default Windows dialog, will appear every time you save a document. You'll have to constantly choose to use the system dialog instead.
Setting the GW client as the default is sufficient to use "file->send". There's a registry hack that might be required for Office 2000, as I recall, if you get a specific error message.