Do I need a voltage converter in S E Asia?
 

Do I need a voltage converter or just the little plugs throughout S E Asia?

It depends on what you wish to plug in. Most modern charger type devices (for computers, MP3 players, cell phones, battery chargers, etc.) will operate from 100-240 volts and 50-60 Hz. In which case you would only need an adapter plug. Check the specifications on each device to ensure it will accommodate the current in your destination country/ies.

Some devices either will not operate or may be harmed if you plug them into wall current in country. If so, you may then need a voltage converter. Again, check the specification plate on each device.

Note that converters do not change the hertz so, for example, a plug in clock which works in the US will not operate on 50 Hz power (well, it may, but probably will run 17% slower).

Forgot to add, good information on available power and sockets around the world can be found at http://www.kropla.com/electric2.htm