You said you want the laptop to last for 4 years for gaming? Good luck with that.
The 3GB of RAM is fairly meaningless, considering you're only going to be gaming at 1600x900. Oblivion, fairly heavily modded, does not go over 1GB at 1920x1080, depending on AA/AF etc.
Look at the http://www.anandtech.com/bench/Mobile/156 section at Anandtech at the different quality levels for gaming. You'll notice most laptops basically svck with modern video games, let alone games coming out in four years.
Basically if you have to stick with a laptop, you need to get the best GPU you can. And a 445M or whatever is not going to cut it. You'd probably need a 485M if you want to game for four years on your laptop, and that's still probably stretching it. A decent (and cheaper) alternative would be the 470M, it's actually newer and faster than the 460/480M despite the naming scheme. You could also go with Mobility 6970 which is just as good as the 485M. Anything less will barely give you a gaming experience with the current games.
I cannot find a 485m in a laptop, four years was a estimate, lets not forget the rest of this laptops specs, along with the cpu and ram, it should last, what maybe 2 years then?
The trouble is i guarantee, most of the people here are desktop gamers and are comparing the two, i am not trying to get a laptop as good as a desktop for gaming, but a laptop which is a decent machine, but all help is appreciated though guys.