Sorry for late reply,
Yes, I need to add 'export http_proxy=http://......' to .bashrc and relogin, and Google-earth works well. And as you mentioned, hanumizzle, it only works from terminal. vpackager also works only from terminal as root. So, M0E, is it any other way to modify the vpackager setting to run vpackager from xfce menu? However, It's just fine to run vpackager from terminal (for me, I'm happy enough), but if we can run it from xfce menu, it would be better for reliability. Now, I'm running vpackager for compiz, hope everything works fine.
(Oh, I also have to add 'export FTP_PROXY=ftp://.....' for vpackager to access ftp server).
Thanks for your kind help,