Allow this device to bring the computer out of standby - means that when the network card receives any traffic it will come out of standby.
Only allow management stations to bring the computer out of standby - means that you must send the network a magic packet to bring it out of standby, this stops random probes from your router waking it up.
just wondering, what is the magic packet which needs to be sent? does it just do this automatically when someone turns their pc on?