What the SETI@home system has shown us, is that there are no earth-like(in 
terms of electromagnetic broadcast) inhabited system within a distance of 
about 400 light years. There are no alien civilisations deliberately 
beaming messages aimed at us within about 5000 light years.

This means we know with reasonable certainty that the local 0.000000001 
percent of our galaxy does not contain an earthlike civilisation at this 
moment in time.

And people consider that as *proof* that extraterrestrial life doesnt 
exist?????

Thats like looking at a square inch of the tarmac in your driveway, and 
basing on the shorage of whales visible in your sample the conclusive proof 
that whales can not possibly exist!