Gameplay is usually not happy without such. But as the designs are changing to where the GPU is fused with the CPU (see AMD's Fusion sets) this will change. While your strict definition of integrated would have us call that integrated it's better than your common integrated video system.
What to do? See the benchmarks.
I'm buying a new laptop. I am not a serious gamer, but I do plan on playing some video games (at least Portal 2). Will I be able to play games without a dedicated graphics card?