You'll find that this is an issue with the PC not having the Asian character sets available to display what the DNS-321 is supplying.
I have a PC that was loaded with these character sets for a visiting Chinese student that was using Internet Explorer. The Asian characters show properly on this PC with iTunes.
The Asian character sets will have to be loaded onto the PCs to display them correctly. I've done this under Windows XP, but not Vista. It's an option in Windows XP and is a matter of just turning it on.
You can search Microsoft's web site for directions on how to load the Asian character sets onto your PCs.