To give you an idea, I play on my desktop but occasionally I'll play on my laptop
Dell XPS 15, i5 CPU (non Sandybridge), 6GB RAM, GTX 420M vid card
It plays the game fine in 1366x768
However, due to the heat, the fan runs in max speed mode.
If I were to play on the laptop for extended periods of time I would use one of those aluminium cooling stands with USB fans.