Joel Reyes posts about the various VSTO SKUs and what project types you get with what SKUs.

The basic principle is that if you only install VSTO 2005 SE you get add-in projects for Office 2003 and 2007 and code behind InfoPath 2007 forms (no 2003 or 2007 document level projects).  To get our Office 2003 document projects for Word, Excel and code behind InfoPath 2003 forms you need to install either VSTO 2005 or VSTS.  Support for Office 2007 document projects won't come until Visual Studio Orcas (the upcoming release of Visual Studio).

Also, Joel says there will be 8 add-in projects in Visual Studio Orcas for Office 2003/2007.  Actually, there will be six for 2003:

Word 2003
Excel 2003
Outlook 2003
PowerPoint 2003
Visio 2003
Project 2003

...and seven for 2007:

Word 2007
Excel 2007
Outlook 2007
PowerPoint 2007
Visio 2007
Project 2007
InfoPath 2007

In addition VS Orcas includes the following "document" or "form level" projects:

Excel 2003 Workbook/Template
Excel 2007 Workbook/Template
Word 2003 Document/Template
Word 2007 Document/Template
InfoPath 2003 Code Behind Form
InfoPath 2007 Code Behind Form

And it includes two SharePoint workflow projects

SharePoint Sequential Workflow
SharePoint State Machine Workflow

I think that covers it...