Sorry but you're out of luck.
I hope you haven't bought another CPU for that laptop already, because if you did you wasted your money. The intel 4 series chipset is an integrated GPU and cannot be upgraded. It's literally soldered into the motherboard and can't be removed or replaced.
The Intel 4 series is most definitely not for gaming. It's for web browsing, business, and watching video and that's about it. Most laptops have chipsets like this and can't be upgraded. If you want a PC you can upgrade, you need to buy a tower or get a custom made laptop with a dedicated CPU and GPU installed.
Your GPU is nowhere near good enough. The game will run like absolute crap if it runs at all. The 2.3 CPU is also below the minimum requirements. Upgrading it won't help because the GPU isn't good enough to run the game anyway. Upgrading the CPU won't make up for that. You'll be lucky if BF 3 even loads and if it does it will be unplayable.
Don't waste your money, you're not going to be able to play BF 3 on that laptop ever. There is no tweak or trick that will make the hardware good enough, it can't be upgraded, and you can't turn the settings in the game down enough to run it.
What you have will barely run Painkiller, Serious Sam [not SS HD], Portal, or Doom 3, much less Battlefield 3.
