>The applications that I am going to create will be in both English and Chinese UI. Some of them are required to be English-Chinese switchable. May I know if the MM .NET framework supports DBCS?

It does...as the following links point out, both Windows Forms and Web Forms are Unicode-enabled allowing for double-byte characters:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vbcon/html/vbconunicodecharacterdisplayinwfcprojects.asp

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vbcon/html/vbtskselectingencodingforwebformsglobalization.asp

Regards,