For sure there are aliens out there. If we discover them is another question. ;-)
My computers have some unused cpu time. I think that it is worth it to use it for SETI@home.
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.