I think that this question can be the best answered in a forum about Office programming (in fact VBA).
Even when you are using VB for Net (and don't tell the latter because it is absolute not important for this question and then you get only answers that it is not a VB Net forum)
Visual Basic for Applications (VBA)
http://forums.microsoft.com/msdn/ShowForum.aspx?ForumID=74&SiteID=1(This is a Microsoft MSDN site)
Alternatively, when developing addins for Office 2003 or 2007 products:
Visual Studio Tools for Office
http://forums.microsoft.com/msdn/ShowForum.aspx?ForumID=16&SiteID=1(This is a Microsoft MSDN site)
Success
Cor