I'm trying to figure out what's a good balance of performance and value for my new MBP. I plan on using a lot of Maya, kinemac, Photoshop....and this will be my main computer. I'm trying not to spend over $2000 here. Basically I need to decide among the following configurations. 4gb or 8gb 750GB 5400RPM vs 500 7200RPM 6490M vs 6750M (obviously 2.0 GHz vs 2.2) If none of the above configurations will make a huge difference then forget it.