Thank for your reply and your great program first!!

After many times of try and error, I found that it can upload jpg under ENGLISH WinXP, but not in CHINESE WinXP.

for CHINESE WinXP:
There are no error when uploading jpg file, but when I try to download the jpg file from server, I found that the content of jpg is changed and it can't be opened again. May be it is becasue of the encoding problems?