I don't think there is any 15" laptop with 5hrs of battery life that can max out those games
Just so you know Maz, Doom 3 and HL2 don't require a whole lot of power. A GT 240M can play HL2 on high settings with over 100 FPS. Far Cry 2 will be a little tougher, but it's still doable (definitely on Medium). 5 hours is still going to be a stretch with a Mid-level card, but we can at least get closer.