I have even 2 graphics cards:
Intel HD Graphics 3000
+
AMD Radeon HD 6750M with 1GB GDDR5
Doesn't Windows only use the more powerful card? Or did they enable switching with the new GPUs?
Plays fine on same spec machine for me on native res + medium to high settings. It's a dreadful game though, don't buy it. Single player is less than 4 hours.