The basic idea behind SETI is to search an area of the sky for radio signals that are in some way "organized" and don't come from Earth. One reason why a DC project was needed is that this obviously involves a huge amount of signals. Also, many signals that come from so far away are going to be very weak once they get here. The methods required to separate these weak signals from the normal background noise involve a huge amount of computation which is the other main reason why so much crunch power is needed to do the job. It's not any harder or easier on your PC, it's just a different way to use up spare resources. Personally I perfer folding also since there already have been usable results from the folding project, and there's no doubt going to be more in the future.
Do not meddle in the affairs of archers, for they are subtle and quick to anger.