If you've been a casual fan of the franchise, or have never been able to experience it, Steam's got an incredible sale you'll way to pay attention to. They've got fairly significant savings on pretty much everything involving the franchise on Steam. While not every game is on Steam, most are. You can get the original game, Double Agent, and Chaos Theory for only $2.50 each. Conviction's Deluxe Edition will only set you back $5, while Blacklist is $20. Blacklist will certainly drop in price later, but every $2.50 offering is worth checking out, while Conviction is worth checking out if you like a more action-oriented game and aren't as good at stealth games.