Hi Winan,
Vsftpd is a FTP server that runs as a deamon under RedHat Linux. It's the guy that hangs out in memory listening to ftp ports for incoming ftp request. Wu-ftp is a ftp client that can connect to an ftp server over the internet. I think there are free light versions of wu-ftp for both windows and linux.
For RedHat linux, I use gFTP as my ftp client. GFTP is multithreaded and runs in X under Linux. It is written in Gtk which is the same C++ language in which the Ximian GNOME framework is written. GFTP should be your Linux replacement for wu-ftp-lt under windows.
Regards,
LelandJ