Instead of sorting by date try sorting by name OR by "Date Created" (i.e. don't use Modified Date in your case)...
I used the utility to backup your blog and sorted by date and saw the same thing, that last/bottom post was 12/6/2006. Sigh... so I dug a little more.
The Modified Date on the XML files is based on the "updated" date of the blog post. For what ever reason, your older blog posts were all last updated on 12/6/2006.
So for example, this post,
http://blog.vagabonders-supreme.net/2003/05/pic-above-is-from-tioga-georges-trip.html has the tags;
So the Modified Date on the file is 6/21/2009 but the Created Date on the file is 5/14/2003...
In Windows Explorer, try sorting your file folder by name or Created Date and see if that helps you see all the posts...
Hope this helps,