Answer to: Replace ink cartridge message (surecolor p-800)The picture you included shows the ink level in each cartridge. Second from left is lowest, possibly empty. Replace it.
Answer to: turn my hard drive in a bootable externalThe original MacBook Air has a ZIF/PATA interface, not the more common SATA interface used in later MacBook Airs, MacBook Pros, etc. The only place I could find an external USB enclosure for ZIF/PATA drives from original MBAs is Other World Computing, part number SMBAZIFENC. http://eshop.macsales.com/item/Other%20W... Update: Two additional enclosures: http://www.cubeternet.com/servlet/Detail... http://www.startech.com/HDD/Enclosures/I...-18-USB-20-LIFZIF-CE-Hard-Drive-Enclosure~IDE1810U2Z