A B737-700 First Officer turned the 'B' Hydraulic pumps OFF while intending to turn the Engine Anti-ice OFF. The switch position activation error caused the Yaw Damper to disconnect because the 'B' hydraulic pressure temporarily dropped.

Narrative

First leg of a 3 day trip: I was the flying pilot (hand flying) - on departure I called for engine anti-ice on as we climbed through the cloud deck. Once out of the clouds called for engine anti-ice off. The First Officer accidentaly turned the 'B' hydraulic pumps OFF by accident and restored them back to normal. ([There was] no effect on airplane - no bump etc) a few seconds later the FLIGHT CONT light illuminated on the Master Caution. I transferred control to the First Officer and found the yaw damper switch had tripped off. Ran QRH procedure and re-established yaw damper operation. Logbook showed flight control work had been accomplished - so I called Maintenance Control and discussed the situation (yaw damper) system was normal and we made decision to continue to our scheduled destination (all systems normal). [I] entered in the logbook on arrival. The anti-ice switches are located directly below the 'B HYD Pump switches and they are the same size and shape and in the same relative position when ON. [We] could have been distracted with ATC clearance to climb to 9;000 FT. The reason for the yaw damper switch tripping OFF was due to the fluctuation in hydraulic pressure when the pumps on B system were turned OFF as reported.