What PS3 or computer game should I buy

It depends on what genre you want to play. I myself do not play the PS3, so I cannot give advice there. That said, for adventure or rpg-style games for the computer, try Guild Wars, WoW, the Diablo series, or Runescape. For strategy games, try the Civilization series, the Warcraft series, or the Starcraft series. For the action/shooter genre, try the Halo series, Counterstrike series, Team Fortress series, half-life series, etc. My personal choice would be Homeworld, a real-time strategy game.