Merge Word Documents (Office Interop & .NET) - Keep Formatting

I'm having some difficulty merging multiple word documents together using Microsoft Office Interop Assemblies (Office 2007) and ASP.NET 3.5. I'm able to merge the documents, but some of my formatting is missing (namely the fonts and images). My current merge code is shown below.

private void CombineDocuments() {
object wdPageBreak = 7;
object wdStory = 6;
object oMissing = System.Reflection.Missing.Value;
object oFalse = false;
object oTrue = true;
string fileDirectory = @"C:documents";
Microsoft.Office.Interop.Word.Application WordApp = new Microsoft.Office.Interop.Word.Application();
Microsoft.Office.Interop.Word.Document wDoc = WordApp.Documents.Add(ref oMissing, ref oMissing, ref oMissing, ref oMissing);
string[] wordFiles = Directory.GetFiles(fileDirectory, "*.doc");
for (int i = 0; i < wordFiles.Length; i++) {
string file = wordFiles[i];
wDoc.Application.Selection.Range.InsertFile(file, ref oMissing, ref oMissing, ref oMissing, ref oFalse);
wDoc.Application.Selection.Range.InsertBreak(ref wdPageBreak);
wDoc.Application.Selection.EndKey(ref wdStory, ref oMissing);
}
string combineDocName = Path.Combine(fileDirectory, "Merged Document.doc");
if (File.Exists(combineDocName))
File.Delete(combineDocName);
object combineDocNameObj = combineDocName;
wDoc.SaveAs(ref combineDocNameObj, ref m_WordDocumentType, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing);
}

I don't care necessarily how this is accomplished. It could output via PDF if it had to. I just want the formatting to carry over.