I've been traveling quite a bit lately and the one question I've gotten a lot in Asia and in Europe is around Language Support in Windows Mobile so I thought I'd attempt to address it.
Unlike Windows Vista, Windows Mobile doesn't have a MUI or Multilingual User Interface on a single image that supports double bit characters (Chinese/Japanese) unless you get a device in a region that uses that double bit language.
The question that I get most often is, assuming I use an English language version of the operating system.
Since the Standard and Professional versions of the OS differ I've covered their multi language support independency.
Windows Mobile Standard/Smartphone (Non Touch Screen)
Windows Mobile Professional (Touch Screen)
If you are looking for a phone to support English and double bit characters you have 2 choices.