My opinion is that by using the internet and everybody's free CPU power is a good thing. However what if the aliens transmit their voices/signals using a different frequency, or using a method we've never heard of.... =/
SETI@home and Astropulse are funded by grants from the National Science Foundation, NASA, and donations from SETI@home volunteers. AstroPulse is funded in part by the NSF through grant AST-0307956.