True bloggers know the importance of backups with their blog posts; they’re valuable and should be safe guarded.
Why Microsoft doesn’t have a function to backup your Windows Live Writer stuff is beyond me; and why they’d leave that to third party developers to figure this gaping loop hole— another mystery.
Windows Live Writer only keeps a copy of what you compose with it; it doesn’t keep anything else offline. So, you need to ensure your keeping it, because if you lose Windows Live Writer data - it’s gone. You can thanks the GUID that Microsoft uses on that one.