The i5 3570 is probably the
best value around at the moment.
I'm building a new PC myself at the moment, and I'm thinking of getting a Solid State Drive. They've come down a lot in price, you can get maybe 128GB for ~$100, which is more then enough to story your OS and frequently used programs. If you keep a standard HDD for media storage and less used programs, then the solid state should really improve your loading speeds.
What Motherboard are you going for? I've had difficulty choosing.