I currently participate in both SETI@Home and Einstein@Home with my two PCs.
Thoughts about SETI and SETI@home
1. I participate to keep my machines doing something useful and to help a project that needs it.
2. There are simply too many stars in the sky -- too many possibilities for extraterrestrial life not to exist. Props to the SETI@home researchers for trying to prove it.
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.