How to restore my laptop to original factory install?

I have HP Compaq 6710b with pre installed Vista Business. I downgrade to Windows XP, and I left my recovery partition untouched. Now when I reboot my PC I don't get F11 countdown message, and I can't enter the recovery mode to recover my PC to factory defaults. I don't have recovery disks. My recovery partition is everything I have. I need my Vista.