Building a computer -- CPU or GPU more important?

With Cycles coming to bear – would I be wiser to spend more on a 3rd gen Intel CPU or a high power graphics card with a cheaper CPU?

Any recomendations in building a system?

Both CPU and GPU are important. You should do some research on the net before buying anything so as to not affect your performance in a negative way.
Great combinations are :
Less money: i5 2500k/ Buldozer 8120/8150 + GTX 560TI
More money: anything from i7 2600k up + GTX 580 for now is huge speed and recommended for simple to medium scenes animation.