I would start with Crysis Warhead and Sins of a Solar Empire, then move on to Dragon Age: Origins.
Originally Posted by D3TH.GRUNT
they all look like good games, so if MP is your thing then tf2 asap
Originally Posted by IEATFISH
They're all pretty solid games. Obviously throw on Crysis and crank up the settings for fun. Play Sins and the other single player games. When you feel like you need some interaction, hop on TF2. Some people don't like TF2 but search the forum for TF2 tips and spend a little time and the game will be extremely rewarding. It's like 9 games in one (each class must be played differently).