A bit of consumer advice when it comes to laptops. Buy ALL the CPU and GPU you can afford, and then some. Since laptops aren’t as upgradable, the more you spend now, the more life you get out of it. Go with the 15" MBP, the 13" are Macbook Not-Pros. Avoid Retina just yet, the pixel-doubling isn’t quite worth the price/performance yet. I’ve been running in Bootcamp on my 2008 15", and getting 30-40fps or so, but only because I picked the better specs back then.
what processor etc does your macbook have? My friend got one in 2010/2011 i cant remember which, but he used to play wow on it (i know that doesnt mean much) and currently plays l4d2 and SC2 (sc2 on medium specs), he says he only has a core 2 duo though. Also, he has snow leopard i believe which probably isnt supported right?