Archer using the Xindi database aboard Enterprise
The Xindi database stolen by Enterprise was one of several key intelligence prizes snatched by Starfleet during the search for the Xindi weapon. It contained comprehensive data about the Xindi, who were largely ciphers to both Starfleet and the Vulcan High Command at the time. Knowledge gained from the database heavily influenced Jonathan Archer's response to the Xindi threat.
Circumstances of retrieval
The Xindi database was obtained by Ensign Hoshi Sato from an Osaarian merchant ship. Forcibly downloaded via a comm link as Enterprise flew less than a kilometer away, the database was accessed only with the use of access codes provided by an Osaarian that Captain Archer was holding in the brig. (ENT: "Anomaly")
Usage
Archer not only attempted to use this database in order to locate the Xindi weapon but also used it to learn much about the Xindi themselves, including the different species of which that group was comprised. (ENT: "Anomaly") For instance, it was through this database that he and T'Pol first became aware of the Xindi-Arboreals, as well as Xindi shuttle design specifications. However, other information proved more elusive, as Archer once spent hours merely trying to understand the way in which the Xindi organized their star charts. (ENT: "Extinction") The database also yielded the location of Rajiin's homeworld. (ENT: "Rajiin")