Hey, dude.
Most importantly, what is your budget and what are your necessities? This will determine the kind of advice moderators and other experts will give you. If you're not strapped for cash and really need the mobility of a laptop, go buy a desktop for your gaming and get a decent laptop for work/school/whatever. If you're really not strapped for cash and have a strong back and insist on mobile gaming, go buy an extraordinarily expensive, extraordinarily heavy AlienWare gaming laptop. $3,000 and 15 to 30 lbs. You'll be getting in shape, that's for sure. Finally, if you're on a budget, the experts will probably want some specifics.
Second, I don't know much about the AMD Radeon 6900M, but if you insist on mobile gaming, your integrated graphics card will be your greatest investment, by far. This is a permanent decision in most cases, rather, in the vast majority of cases. Most laptops have rather powerful cpus even when compared to their desktop counterparts, but integrated graphics cards are absolutely horrible in comparison. This is where almost all of your bottle necking will occur. Look for the best compatible mobile graphics card you can get your hands on.
Thirdly, I understand that modern games love their quad-core processors, even though the graphics card is where you will be getting bottle-necked. An i7 is probably the best way to go.
Assuming someone more knowledgeable doesn't notice this thread sometime soon, I would keep your current set up, assuming you're on a budget, and get the best integrated graphics card, AMD or GTX, you can buy.
Below are some helpful tom's hardware articles.
This is about the laptop upgrade solution, vidock.
http://www.tomshardware.com/reviews/vidock-expresscard-graphics,1933.html
This talks about your prospective graphics card candidate, the radeon 6990m.
http://www.tomshardware.com/reviews/eurocom-racer-core-i7-2960xm-radeon-hd-6990m,3105.html
Not on a budget? Great! Read this.
http://www.tomshardware.com/reviews/pc-building-overclocking-buyers-guide,3282.html
On a budget? $500 bucks? Great! Read this.
http://www.tomshardware.com/reviews/gaming-pc-overclocking-pc-building,3273.html
Why i7? Read this.
http://www.tomshardware.com/reviews/core-i7-2920xm-core-i7-980x-sandy-bridge,2851.html
Really, really, really need reasonable mobility, but don't want to loose a single framer-rate? Ambitious as all hell with OCD that refuses anything less than the best? Recently received a massive inheritance? Great! Read this.
http://www.tomshardware.com/reviews/sli-a-notebook-beat-desktop-graphics,1314.html