Works very nicely and doesn't impact the CPU usage at all.
Towne, this is what I use to start the CLI client on the command line:
nohup ./setiathome -nice 19 -email > seti.log &
This tells it to run the client from the directory I'm in (which should be where the client is), don't quit it when I log out (nohup), email me if it wants, send any output to the seti.log file (the '>' sign), and the '&' tells the app to run in the background. Nice of 19 means that anything else can take precedence of the CPU over it, which means everything else will run fine when you use your computer, but it will take all the CPU when nothing else is running.