Get specific window handle using Office interop

I'm creating a new instance of Word using the Office interop by doing this:

var word = Microsoft.Office.Interop.Word.Application();
word.Visible = true;
word.Activate;

I can get a window handle like this:

var wordHandle = Process.GetProcessesByName("winword")[0].MainWindowHandle;

The problem is that code works on the assumption that there's no other instance of Word running. If there are multiple, it can't guarantee that the handle it returns is for the instance that I've launched. I've tried using GetForegroundWindow after detecting a WindowActivate event from my object but this is all running within a WPF application that's set to run as the topmost window, so I just get the handle to the WPF window. Are there any other ways to get the handle for my instance of word?

Not sure why you need the handle to Word, but one way I've done this before is to actually change the Word window caption and search for it. I did this because I wanted to host the Word application inside a control, but that's another story. :)

  var word = new Microsoft.Office.Interop.Word.Application(); 
  word.Visible = true; 
  word.Activate();
  word.Application.Caption = "My Word";

  foreach( Process p in Process.GetProcessesByName( "winword" ) )
  {
    if( p.MainWindowTitle == "My Word" )
    {
      Debug.WriteLine( p.Handle.ToString() );
    }
  }

Once you got the handle, you can restore the caption if you like.