I was asked the other day if SharePoint Designer 2010 will work with 2007 based sites. It looks like SharePoint Designer 2010 is not supporting backward compatibility. Therefore it won’t support Windows SharePoint Services 2007 / v3 or earlier versions. Unfortunately, SharePoint designer 2010 only works for SharePoint 2010. However, you should be able to have both versions installed and running on your computer simultaneously. Is this a correct assumption?