Well just check if you set vista to read japanese script like in windows.
I don't think anyone has tried this yet.
try to do more or less the same settings in vista as in your Xp computer
Although I must say that was obivious.
Usually, winmx will sort things ok by itself, but see if your system is set to read japanese characters in the first place. On XP, as you will know, the settings in under regional settings, see if there is something sililar in vista.
I split the topic as it was a bit off topic and as more than a few users on vista might have the same issue
Cheers