Este é quase certamente o Outernet series. Também li no início / meados dos 2000s. Aqui está um trecho da descrição do primeiro livro da Wikipedia (ênfase minha); Incluo também menções de alguns outros personagens principais e elementos da história (Pão, Merle, Bitz, Googie, Ajuda) no caso de tocarem sinos para você:
On Jack Armstrong's birthday, he received a laptop computer from his parents, British residents working on a US military base. They have been having financial problems so he is grateful for the gift. He explores it with his friend Lothar Gelt (nicknamed Loaf) and their acquaintance Merle Stone, where they discover it is a piece of alien technology. Once turned on, it enables them to communicate with a stray dog around the base named "Bitz", who tells them he is actually code-named Sirius (a pun on the "Dog Star" of the same name). He and Merle's apparent cat (named Googie, code-name Vega), are both members of the "Friends", a group dedicated to resistance of The Tyrant, who leads the FOEs (Forces of Evil). Specifically, they are shape-shifters who have become permanently trapped in these Earth creature forms. They explain how The Tyrant has captured all of the servers in the Galaxy except for the one that Sirius and his companion Janus brought to Earth and disguised as the computer. The Server's "Help" program, which activates whenever its name is said, is sardonic and fails to live up to its name. Jack receives further proof of the truth of these odd revelations when he is teleported (called t-mailed) to meet Janus on another planet (teleportation through "N-Space" enables the characters to travel faster-than-light).
Ao longo da série, Jack e os outros personagens principais viajam pelo Galaxy sendo perseguidos pelos FOE, tentando permanecer vivos e, finalmente, derrubar o Tyrant e os FOE. A viagem no tempo se envolve no livro 4 ou 5, e há algumas reviravoltas surpreendentes no final.
A Wikipedia também menciona:
The book series asked the readers to access an internet site named www.go2outer.net. That site is no longer active and, in fact, is for sale.
Não me lembro dos detalhes, mas havia algumas coisas interativas divertidas que você poderia fazer naquele site, jogando como se você fosse um membro dos Amigos trabalhando contra os FOE.