Just released, Visual Studio 2005 tools for Office 2007 SE (Beta). This seems like a nice addition to Visual Studio 2005. And even though it says Office 2007 it also works for creating Office 2003 addins, including Word, Excel, Outlook, PowerPoint and Visio.
And the best thing is that it is a free download. Well almost, you need to have a licensed copy of VS2005 Pro or higher or VSTO 2005 so the Express developers are out of luck this time.
Download it from: http://www.microsoft.com/downloads/details.aspx?FamilyId=5012A573-0D84-4E39-983C-CA22F2107B07&displaylang=en
Maurice de Beijer