You're going to have to figure out the overclocking yourself and if it's safe/worth it for you to do that or not. You technically can use OSX, but Windows x64 will perform better. Either way, with your current setup, you may gain a little extra speed by overclocking but a faster processor is needed. Try some other games and see what speeds you get.
Asus Laptop: K53TA
OS: Windows 7 Home Premium, 64-Bit - SP1
CPU: AMD Llano A6-3400M, Quad-Core, 1.4GHz-2.6GHz (Overclocked)
GPU: AMD Radeon HD6650M, 1GB GDDR3 (Catalyst 13.1)
RAM: Samsung 4GB DDR3-1333
OS: Windows 7 Home Premium, 64-Bit - SP1
CPU: AMD Llano A6-3400M, Quad-Core, 1.4GHz-2.6GHz (Overclocked)
GPU: AMD Radeon HD6650M, 1GB GDDR3 (Catalyst 13.1)
RAM: Samsung 4GB DDR3-1333