Do you have Windows XP or Windows 7 and your language on the machine is set to Vietnamese or Arabic?
If so, we'd like to know what IE's default charset setting is?
I'm posting this for someone else. He is testing IE defaults and rendering modes.
I do know someone that uses a computer with a Chinese Windows... would that be of any help?
He was specifically asking for Vietnamese or Arabic, so I assume he's already found the answer for Chinese.