InfoPath Dev

I have a form that is going to be updated on a regular basis and I would like to be able to reflect the date a certain text box was last updated for use in a dashboard.  I have some C# experience but I'm not sure the best way to go about it.  I'm not sure if the 'Changed' event will be able to handle it or what.  Any guidance would be greatly appreciated (Infopath 2007)

Yes, putting something like this in the textbox's changed event would do the trick:

XPathNavigator dateNode = MainDataSource.CreateNavigator().SelectSingleNode("XPath to date node", NamespaceManager);

// Delete the xsi:nil attribute if it is present
XPathNavigator nilAttribute = dateNode.SelectSingleNode("@xsi:nil", NamespaceManager);
if (nilAttribute != null)
{
     nilAttribute.DeleteSelf();
}

dateNode.SetValue(XmlConvert.ToString(DateTime.Now,"yyyy-MM-dd"));

Looks like it worked just fine, thank you very much - do you know of a good site or book to explain working with XML and C#?  My C# is a littel rusty but I have very little experience coding with XML

I don't, unfortunately, but I learned almost all of what I know just by tinkering around a lot.  For coding with XML in InfoPath, reading the up on the XPathNavigator class will get you a long way.  It's nearly the only XML-related class you'll need to use with InfoPath, and by far the most important methods are SelectSingleNode() and Select():

http://msdn.microsoft.com/en-us/library/system.xml.xpath.xpathnavigator.aspx
http://msdn.microsoft.com/en-us/library/bb509311.aspx
http://support.microsoft.com/kb/308343

It's a bit dry, but I'd also suggest reading the W3C document on XPath.  It illuminates a lot of XPath's capabilities:

http://www.w3.org/TR/xpath