Help review my first arduino PCB: What did I do wrong?
If your worried about noise, make sure you look at return current paths. The ground should be solid and provide a clear pathway to run back to the source (pin 6 on the 0.1" header)

The vias that run between the discontinuous ground planes add 5-10nh of inductance and a few milliohms of resistance. The key is to be aware of it, if your having problems that might be the source. Print the schematic out and draw the vias in as inductors/resistors and see if that poses a problem for the design. 

The orange line shows roughly the path the return current from IC1, it doesn't look great as there is only one via on it's return. 

Make at least the left hand side of the board a continuous ground. 



The ground plane doesn't look great, it may not matter, but if there is a problem it may be hard to track down.