Why do you run SETI@home?
I'm really running SETI@home because I thought that the idea of using a worldwide distributed computer network to try to process the massive quantity of data that SETI has gathered was both novel and well considered. I've always thought that the SETI project is something that simply has to be.
Thoughts about ETI
I don't think that anyone can rationally believe that humans are the only intelligent life form in the universe. Only a project such as SETI has much hope of detecting that rational, non-random signal that we are all looking for. Sure, we may be opening Pandora's Box (there's always a place for a tested cliche), but there's every reason to think that the box will eventually be opened with or without our assistance. I have no qualms about setting up a project that would transmit a signal that could can only be interpreted as coming from a rational origin.
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.