Good MOSFET for high-side switching 200mA from 5V logic
As I understand it your circuit is wrong - it's showing an N channel mosfet wired as a source follower and this means you're likely to get about 2 or 3 volts out of it when "switched on".

You need a p channel mosfet with source tied to incoming power and drain connected to the output. Pulling the gate low will activate the FET, returning the gate to 5V will deactivate the fet but make sure you get one with \$V_{GS(threshold)}\$ quite low - maybe about -1V typical and -2V max. 

The device Wouter has linked (IRF7205) might work OK but it's threshold range might mean sometimes it doesn't work (if you built a hundred maybe 5 wouldn't work as expected).