Laptops aren't really meant for gaming.
Anyways, spend a good $1200~$1500 on an i7 build, and you will NOT be disappointed.
i7 920 is 4 Cores but hyper threaded so it acts like an Octocore (Eight Cores!!!).
Trust me a good i7 build will run several light years ahead of your current laptop.
Its not about who can shell out the most coin when it comes to building your own computers. There is also a price/performance ratio involved. Which is part of the reason no one has recommended the GTX 280 as of yet.