A Bad Day said:
If you're wanting to game at a budget, I would recommend going with a high end i5. Usually laptops with the i5s are cheaper than the i7s, yet have similar performance because most games don't use HyperThreading.
All games can use Hyper-Threading. They tend to not use it much on Intel's quad-core CPUs because they don't scale well across eight threads.
Mobile i5s are all dual-core models (they're basically just mobile i3s except with Turbo, more cache, and PCIe 3.0 support), so you do not want to get one of them. It'd be almost as bad as going from a desktop i5 to a desktop i3.