Well, (at least in the U.S.) you probably won't find a decent laptop under $300, and that's with all the basic stuff, and certainly not enough to play that. You need a good processor (I run an intel i5). Also, for premium performance, you will want a high quality graphics card. All I can say is don't cheap out on the laptop, or you wont be happy with how the game works and then you'll have to buy a new one. The secret on saving money: The secret is to go to the supplier's website. That way you arent buying from a middle man. I bought my laptop online, and saved over $200-$300!!! Don't get me wrong, laptops are not cheap, but I got a Dell with the new (at least when I posted for those reading years later) intel i5 processor, 17.3" screen, backlit keyboard (20 bucks extra), windows 7 home premium, 9 cell battery, JBL premium sound, HD webcam, and a whole bunch of other techy stuff. All for $800 ($860 with tax) but would have normally spent over $1100-$1200. Well, anyways sorry if i bored you.
If you have the time and willingness, you should look into assembling your own computer. It's cheaper and the experience is valuable. Especially good if you plan on getting a high-end system for gaming and that stuff. Generally you can save a few hundred dollars if you purchase your own parts.
Gaming laptops are suitable if you're on the move a lot. Otherwise stick with a desktop.
What are the specs of your computor right now? If you odn't know how to check, click the start button, then my computor, and view system information.
It will tell you ever thing you need to know. I'm not sure how hardcore this game is, so if you could give me the specs, I have some time to blow looking for good computors.
And look on G4. They do a thing called gadget pron, i'm not sure if you can find the link, but they had 300$ netbooks, they said could run new high end games on medium quality. So I'd say its something worth checking into.
I would highly recommend a Toshiba Satellite. My mom just got one for herself and I was very impressed. It was very light, ran games very well, and didn't get too hot.