I'm looking to buy a new MBP and I wanted to know if there was a big difference from the "low end" to the "high end" especially with the new penryn processors. For example, if I had to MBP in front of me, both upgraded to 4GB RAM, is there going to be a significant performance difference. I intend to do some video and photo editting and I play games rarely. I will be an engineering and pre-med student so I'll need some CPU power to run the engineering programs. And there's a good chance that I'll need to run windows for proprietary engineering programs that are made only for Windows. So in the end, is it worth the extra $500?