The following are important factors when considering using SharePoint Designer to customize and design your SharePoint sites:
• The current version of SharePoint you are running.
• Whether, as part of your SharePoint Server 2007 or Windows SharePoint Services 3.0 to SharePoint 2010 upgrade, you might be required to also upgrade earlier customizations done using SharePoint Designer 2007 to SharePoint Designer 2010. This might include Data View Web parts, master pages, and CSS files.
• You have other, non-SharePoint, websites, such as ASP.NET 2 websites, that you also want to customize and design using SharePoint Designer.
In the first instance, you need to be aware that SharePoint Designer 2010 cannot be used ...