XP-tan has blue eyes and ribbons in her long hair with an "XP" hair ornament. Her hair color can be brown, black or blue. 
She wears a stylized white and blue school uniform and has large breasts. She is envied for her beauty by her sisters. 
XP-tan is often seen eating or holding an empty bowl labeled "Memory".
XP-tan is promiscuous and a big glutton. She used to be not very useful, but she became more reliable over time.

XP-tan's nickname is "Saseko".

OS-tan for Windows XP Pro.

Me-tan has green hair in long braided pigtails, green eyes and wears a maid outfit with brown loafers without socks and an exclamation mark badge on the front modeled after the Windows error icon. She carries a scallion to defend herself from malware. A hard worker who always wants to help her Master(Toshiaki), but she's clumsy. She crashes and freezes often. She tends to do things showing a lack of common sense. She is cheerful and optimistic.