As with almost all laptops, replacing anything other than adding memory is extremely difficult. That said, the dual-core Pentium and Intel HD Graphics (128MB video memory), are much better than most laptops anywhere near this price point. Not to mention the 16:9 aspect ratio and number keys.
Laptops aren't known for being very upgradable or expandable (except for an expansion slot on some or swapping RAM). Replacing a processor is not a simple task, even if you find a compatible one. And even then you're wasting your money (spend it instead on a different laptop). Integrated graphics would be part of the motherboard, not sure if there's an expansion slot for another graphics card but if you want something for gaming, don't get this laptop. Spend your graphics and CPU money towards a higher end laptop.