I need help picking a hardware configuration. I have experience in hardware with iPhones, but not with computers, I am willing to spend around $500-$600 and I need it to be able to handle photoshop CS5 well, To be able to Edit video well, and I am considering getting into gaming so I would prefer a Nvidia Graphics card. I need everything to work, especially sound and wireless. and of Course, Snow Leopard.

For reference, I am currently using a white macbook 2.4 C2D from 2008.